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  • 1
    Electronic Resource
    Electronic Resource
    Sexual maturation in female rats: Hereditary, developmental and environmental aspects (1991)
    Springer
    Cellular and molecular life sciences 47 (1991), S. 1026-1038 
    Details
    ISSN: 1420-9071
    Keywords: Development ; heredity ; lighting environment ; melatonin ; puberty ; rat ; Roman Low Avoidance ; Roman High Avoidance ; stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Two physiological components of sexual maturation, vaginal opening and first estrus, apparently evolve similarly in Wistar and Sprague-Dawley rats. However, a bimodal distribution in the frequency of the days of vaginal opening is observed within a given strain, which is less related to heredity than to the timing and type of experiment. In addition, when the modulators of sexual maturation are reviewed, it can be observed that sensitivity to external stimuli can vary even within a strain. For a defined set of breeding conditions, one group of rats can be more susceptible to changes in the lighting regimen and not be affected by controlled stressors, while another group responds more to stress and less to light. The reason for susceptibility to one rather than another environmental factor under similar breeding conditions is not understood. In that context, it is difficult to evaluate the role of heredity when we cannot understand the full impact of the environment, not to mention maternal influence in fetal and early life. Using two lines of psychogenetically selected rats, it was possible to show that they had differences in sexual maturation, which strongly suggested a genetic predisposition. Nevertheless, the question arises as to whether the genetic locus directly affects organs implicated in sexual maturation or whether it acts on some unknown factor which only secondarily modifies sexual maturation. In summary, there is more need to understand the role of the environment, including that of the mother early in fetal and neonatal life. It is suggested that the mechanisms underlying organ growth are set for a given species, while developmental and environmental factors fix the timing of vaginal opening and first ovulation. In the rat, there appear to be two times which are preferred for vaginal opening, given the laboratory conditions that have been used in the last 20 or so years: an early period, at 31–35 days, and a late period, at 36–40 days. An explanation for this dichotomy would be that a combination of parameters (not necessarily always the same) is needed for vaginal opening. These parameters oscillate during sexual maturation with different frequencies, which can achieve resonance to lead to vaginal opening and ovulation only during given periods.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01923338
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  • 2
    Electronic Resource
    Electronic Resource
    Moth ocellar interneurons show abnormal development in the absence of receptor innervation (1985)
    Springer
    Cellular and molecular life sciences 41 (1985), S. 111-112 
    Details
    ISSN: 1420-9071
    Keywords: Development ; interneurons ; moth ; ocellus ; Trichoplusia ni ; Lepidoptera: Noctuidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Unilaterally ocellate adult moths were produced by cauterization of one of the pair of ocellar primordia in fifth instar larvae. The remaining ocellar nerves and associated interneurons of the adult moths were subjected to cobalt infiltration and Timm's intensification. Two interneurons from the ablated ocellus were observed to grow into the synaptic region of the remaining ocellus and presumably made functional connections with ocellar receptor cell axons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02005903
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  • 3
    Electronic Resource
    Electronic Resource
    Osteocyte types in the developing mouse calvarium (1973)
    Springer
    Calcified tissue international 12 (1973), S. 259-279 
    Details
    ISSN: 1432-0827
    Keywords: Osteocyte ; Calvarium ; Histology ; Development ; Calcium ; Phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Des cartes tissulaires ainsi que les caractéristiques et propriétés cellularires ont été relevées au cours d'une étude de microscopie optique du développement de la calotte cranienne de souris, avant la naissance, jusqu'au 26ème jour. Les population d'ostéocytes de moitiés droite et gauche de ces calottes sont semblables, mais décroissent avec le temps dans un volume donné. De petites plages limitées de matrice osseuse se colorent pour le phosphate (ou carbonate) de façon plus nette que la matrice environnante, qui se colore légèrement après coupe. Les divers types ostéocytaires se distinguent par les réactions histochimiques du calcium et du phosphate, qui sont associés dans les cellules osseuses de façon complexe, variant dans le temps et la localisation. Ces deux constituants ne sont pas toujours présent dans les cellules des diverses régions, ou dans la même localisation dans un type cellulaire donné. En tenant compte des changements visible dans les divers types cellulaires avec le temps, dans des régions données, une hypothèse de “charge” et “décharge” cellulaire est émise.
    Abstract: Zusammenfassung Anläßlich einer mikroskopischen Studie über die Entwicklung des Mäuse-Calvariums von der Pränatalperiode bis zu 26 Tagen nach der Geburt wurden auch die Gewebetopographie sowie die Charakteristica und Eigenschaften der Zellen aufgezeichnet. Die Osteocyten-populationen in der linken und rechten Hälfte des Calvariums waren sich gleich, nahmen jedoch bei einem gegebenen Volumen mit der Zeit ab. Kleine isolierte Stellen von Knochen-matrix konnten leichter auf Ph sphat (oder Carbonat) angefärbt werden, als die umgebende Matrix, welche sich wohl am Schnitt, nicht aber am ganzen Stück färben ließ. Die verschiedenen Typen von Osteocyten wurden aufgrund histochemischer Calcium- und Phosphat-reaktionen bestimmt. Calcium und Phosphat waren innerhalb der Knochenzellen auf komplexe Art miteinander verbunden, die je nach Zeit und Lagerung unterschiedlich war. Zellen in abgetrennten Bereichen enthielten nicht immer Calcium und Phosphat und beide waren bei einer bestimmten Zellenart auch nicht immer am gleichen Ort abgelagert. Aufgrund der an ausgewählten Stellen beobachteten, zeitlich bedingten Veränderungen innerhalb der verschiedenen Zelltypen wird vorgeschlagen, daß es sich dabei um eine Sequenz von “Ladung” und “Entladung” der Zellen handelt.
    Notes: Abstract Tissue maps, and cell characteristics and properties were recorded in a study under the optical microscope of the development of the mouse calvarium from pre-natal to 26 days. Osteocyte populations in left and right halves of the calvarium were similar, but decreased with time for a given volume. Small isolated areas of bone matrix stained for phosphate (or carbonate) in a more readily available form from that in the surrounding matrix, which could be stained after sectioning but failed to stain in bulk. Osteocyte types were defined on the basis of histochemical methods for calcium and phosphate, which were associated inside bone cells in a complex manner, varying with time and position. The calcium and phosphate were not always present within the cell in discrete regions and were not always present in the same place in a given cell type. On the basis of a study of changes in cell types with time in selected sites a sequence of “loading” and “unloading” is proposed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02013740
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  • 4
    Electronic Resource
    Electronic Resource
    Mucopolysaccharides and collagen in prenatal and postnatal human development (1974)
    Springer
    Calcified tissue international 16 (1974), S. 209-217 
    Details
    ISSN: 1432-0827
    Keywords: Mucopolysaccharides ; Collagen ; Calvarium ; Development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract Mucopolysaccharides (MPS) and collagen have been analyzed in different types of cartilage and some other tissues at various stages of prenatal and postnatal human development. The concentration of the chondroitin sulfate-type MPS increased from the 38th embryonal day, the 6-sulfate exceeding in amount the 4-sulfate. The increase in collagen concentration was accompanied by a decrease in the proportion of neutral salt-soluble collagen. There was no accumulation of chondroitin sulfates in the calvaria. A maximal concentration of MPS of a low molecular weight occurred in the skin and in the ear pinna after the 10th prenatal week. Postnatally, the MPS-concentration in the iliac crest and in the tibial articular cartilages decreased gradually, the highest values being reached in the newborn; the collagen-concentration showed an approximately reciprocal course.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02008228
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  • 5
    Electronic Resource
    Electronic Resource
    Effects of maturation on synaptic potentials in the locust flight system (1994)
    Springer
    Journal of comparative physiology 175 (1994), S. 437-447 
    Details
    ISSN: 1432-1351
    Keywords: Insect ; Motor pattern ; Development ; EPSP Synaptic depression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract We have measured parameters of identified excitatory postsynaptic potentials from flight interneurons in immature and mature adult locusts (Locusta migratoria) to determine whether parameters change during imaginal maturation. The presynaptic cell was the forewing stretch receptor. The postsynaptic cells were flight interneurons that were filled with Lucifer Yellow and identified by their morphology. Excitatory postsynaptic potentials from different postsynaptic cells had characteristic amplitudes. The amplitude, time to peak, duration at half amplitude and the area above the baseline of excitatory postsynaptic potentials did not change with maturation. The latency from action potentials in the forewing stretch receptor to onset of excitatory postsynaptic potentials decreased significantly with maturation. We suggest this was due to an increase in conduction velocity of the forewing stretch receptor. We also measured morphological parameters of the postsynaptic cells and found that they increased in size with maturation. Growth of the postsynaptic cell should cause excitatory postsynaptic potential amplitude to decrease as a result of a decrease in input resistance, however, this was not the case. Excitatory postsynaptic potentials in immature locusts depress more than in mature locusts at high frequencies of presynaptic action potentials. This difference in frequency sensitivity of the immature excitatory postsynaptic potentials may account in part for maturation of the locust flight rhythm generator.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00199251
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  • 6
    Electronic Resource
    Electronic Resource
    Activity of the forewing stretch receptor in immature and mature adult locusts (1994)
    Springer
    Journal of comparative physiology 175 (1994), S. 425-435 
    Details
    ISSN: 1432-1351
    Keywords: Insect ; Flight ; Development ; Motor pattern Afferent
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Maturation of the flight system of Locusta migratoria occurs during the first two weeks following imaginal ecdysis. One aspect of maturation is an increase in the wingbeat frequency from about 13 Hz to about 23 Hz. We investigated physiological and anatomical mechanisms that may contribute to this process. The difference between the frequencies of the central flight rhythms of immature and mature deafferented preparations was not as great as that between the wingbeat frequencies of immature and mature intact animals. Results from static and dynamic wing elevation showed that the intensity of the forewing stretch receptor response to a given stimulus increased during maturation. The diameter of the main stretch receptor axon was larger and the conduction velocity of signals conveyed along the forewing stretch receptor and the dorsal longitudinal motoneuron was faster in mature than in immature animals. We conclude that during maturation of the flight system the forewing stretch receptor responds to wing elevation with a higher frequency signal that reaches the central circuitry faster. These findings are discussed in the context of a model that describes the influence of stretch receptor input on wingbeat frequency along with other potential mechanisms involved in flight maturation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00199250
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  • 7
    Electronic Resource
    Electronic Resource
    Ontogeny of the electric organ discharge and the electric organ in the weakly electric pulse fish Brachyhypopomus pinnicaudatus (Hypopomidae, Gymnotiformes) (1997)
    Springer
    Journal of comparative physiology 181 (1997), S. 111-119 
    Details
    ISSN: 1432-1351
    Keywords: Key words Weakly electric fish ; Gymnotiformes ; Development ; Electric organ ; Electric organ discharge
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract I recorded the electric organ discharges (EODs) of 331 immature Brachyhypopomus pinnicaudatus 6–88 mm long. Larvae produced head-positive pulses 1.3 ms long at 7 mm (6 days) and added a second, small head-negative phase at 12 mm. Both phases shortened duration and increased amplitude during growth. Relative to the whole EOD, the negative phase increased duration until 22 mm and amplitude until 37 mm. Fish above 37 mm produced a “symmetric” EOD like that of adult females. I stained cleared fish with Sudan black, or fluorescently labeled serial sections with anti-desmin (electric organ) or anti-myosin (muscle). From day 6 onward, a single electric organ was found at the ventral margin of the hypaxial muscle. Electrocytes were initially cylindrical, overlapping, and stalk-less, but later shortened along the rostrocaudal axis, separated into rows, and formed caudal stalks. This differentiation started in the posterior electric organ in 12-mm fish and was complete in the anterior region of fish with “symmetric” EODs. The lack of a distinct “larval” electric organ in this pulse-type species weakens the hypothesis that all gymnotiforms develop both a temporary (larval) and a permanent (adult) electric organ.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003590050098
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  • 8
    Electronic Resource
    Electronic Resource
    Ontogeny of rhythmic motor networks in the stomatogastric nervous system (1999)
    Springer
    Journal of comparative physiology 185 (1999), S. 361-365 
    Details
    ISSN: 1432-1351
    Keywords: Key words Central pattern generators ; Development ; Homarus gammarus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract We used the lobster Homarus gammarus to study the ontogeny of neural networks involved in rhythmic behaviours. Since in the adult the neural networks belonging to the stomatogastric nervous system and controlling the rhythmic movements of the foregut are well characterised, we have studied them during ontogeny. While this foregut develops slowly throughout embryonic and larval stages, the neuronal population of these motor networks is quantitatively established since the mid-embryonic period. Moreover, in the embryo, this neural population is organised into a single functional network that displays a unique motor output. By contrast, in the adult the same neuronal elements are organised into three neural networks that express independent motor programs. Our results indicate that the multiple adult networks are partitioned progressively from a single embryonic network during development.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003590050395
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  • 9
    Electronic Resource
    Electronic Resource
    A nose that looks like a hand and acts like an eye: the unusual mechanosensory system of the star-nosed mole (1999)
    Springer
    Journal of comparative physiology 185 (1999), S. 367-372 
    Details
    ISSN: 1432-1351
    Keywords: Key words Cortical magnification ; Somatosensory cortex ; Development ; Evolution ; Behavior
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The star-nosed mole (Condylura cristata) has a snout surrounded by 22 fleshy and mobile appendages. This unusual structure is not an olfactory organ, as might be assumed from its location, nor is it used to manipulate objects as might be guessed from its appearance. Rather, the star is devoted to the sense of touch, and for this purpose the appendages are covered with thousands of small mechanoreceptive Eimer's organs. Recent behavioral studies find that the star acts much like a tactile eye, having a small behavioral focus, or “fovea” at the center – used for detailed explorations of objects of interest. The peripheral and central nervous systems of the mole reflect these behavioral specializations, such that the small behavioral focus on the nose is more densely innervated in the periphery, and has a greatly enlarged representation in the somatosensory cortex. This somatosensory representation of the tactile fovea is not correlated with anatomical parameters (innervation density) as found in other species, but rather is highly correlated with patterns of behavior. The many surprising parallels between the somatosensory system of the mole, and the visual systems of other mammals, suggest a convergent and perhaps common organization for highly developed sensory systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003590050396
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  • 10
    Electronic Resource
    Electronic Resource
    Postmetamorphic changes in auditory sensitivity of the bullfrog midbrain (1995)
    Springer
    Journal of comparative physiology 177 (1995), S. 577-590 
    Details
    ISSN: 1432-1351
    Keywords: Metamorphosis ; Anuran ; Audiogram ; Development ; Midbrain
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract During metamorphosis, the lateral line system of ranid frogs (Rana catesbeiana) degenerates and an auditory system sensitive to airborne sounds develops. We examined the onset of function and developmental changes in the central auditory system by recording multi-unit activity from the principal nucleus of the torus semicircularis (TSp) of bullfrogs at different postmetamorphic stages in response to tympanically-presented auditory stimuli. No responses were recorded to stimuli of up to 95 dB SPL from latemetamorphic tadpoles, but auditory responses were recorded within 24 hours of completion of metamorphosis. Audiograms from froglets (SVL 〈 5.5 cm) were relatively flat in shape with high thresholds, and showed a decrease in most sensitive frequency (MSF) from about 2500 Hz to about 1500 Hz throughout the first 7–10 days after completion of metamorphosis. Audiograms from frogs larger than 5.5 cm showed continuous downward shifts in MSF and thresholds, and increases in sharpness around MSF until reaching adult-like values. Spontaneous activity in the TSp increased throughout postmetamorphic development. The torus increased in volume by approximately 50% throughout development and displayed changes in cell density and nuclear organization. These observations suggest that the onset of sensitivity to tympanically presented airborne sounds is limited by peripheral, rather than central, auditory maturation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00207187
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  • 11
    Electronic Resource
    Electronic Resource
    The effect of genotype, age, sex, and caste on response thresholds to sucrose and foraging behavior of honey bees (Apis mellifera L.) (1999)
    Springer
    Journal of comparative physiology 185 (1999), S. 207-213 
    Details
    ISSN: 1432-1351
    Keywords: Key words Honey bee ; Behavior ; Development ; Neurobiology ; Foraging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Bees derived from artificially selected high- and low-pollen-hoarding strains were tested for their proboscis extension reflex response to water and varying sucrose concentrations. High-strain bees had a lower response threshold to sucrose than low-strain bees among pre-foragers, foragers, queens and drones. Pre-foraging low-strain workers showed ontogenetic changes in their response threshold to sucrose which was inversely related to age. High-strain foragers were more likely to return with loads of water compared to low-strain foragers. Whereas low-strain foragers were more likely to return with loads of nectar. Low-strain nectar foragers collected nectar with significantly higher sucrose concentrations than did the high-strain nectar foragers. Alternatively, low-strain foragers were more likely to return empty compared to high-strain foragers. These studies demonstrate how a genotypically varied sensory-physiological process, the perception of sucrose, are associated with a division of labor for foraging.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003590050379
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  • 12
    Electronic Resource
    Electronic Resource
    Ontogeny of the rhythmic melatonin production in a precocial and an altricial bird, the Japanese quail and the European starling (1993)
    Springer
    Journal of comparative physiology 172 (1993), S. 333-338 
    Details
    ISSN: 1432-1351
    Keywords: Development ; Pineal ; Circadian rhythm ; Birds
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract A distinct daily rhythm of melatonin production was found in the pineal gland of both precocial Japanese quail (Coturnix coturnix japonica) and altricial European starling (Sturnus vulgaris) during the first day of postembryonic life. Rhythmic melatonin production was reflected in a rhythmic profile in the general circulation. Significant day-night differences in melatonin content were also observed in the eyes of Japanese quail. The amplitude of the rhythm in the quail pineal gland increased steadily during the first two weeks of postem-bryonic life. A transient increase in maximum melatonin concentration was observed at the end of the first week of life in the plasma but not in the pineal gland of quail suggesting that a metabolizing pathway or a changed ocular contribution may influence the melatonin profile in the circulation and its availability to other tissues. There was no delay in the postembryonic development of melatonin rhythmicity in the altricial starling in comparison with the precocial quail. The amplitude of the plasma melatonin rhythm did not increase over the first week of life in starlings as it did in quail and the only significant increase was found between 6- and 17-day old starlings. In general, the development of the rhythm resulted from an increase of dark-time values. The day-time concentrations were low in all age groups of both species. A one-hour light pulse suppressed the high dark-time melatonin concentrations in 1-, 7- and 14-day old Japanese quail as well as in 7- and 14-day old European starlings. The manner in which the rhythm develops suggests that the circadian pacemaker(s) as well as the mechanisms of photoreception and entrainment are developed in hatchlings of both species in spite of their otherwise different developmental strategies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00216615
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  • 13
    Electronic Resource
    Electronic Resource
    Proprioceptive feedback in locust kicking and jumping during maturation (1996)
    Springer
    Journal of comparative physiology 179 (1996), S. 195-205 
    Details
    ISSN: 1432-1351
    Keywords: Sensory ; Motor pattern ; Development ; Grasshopper ; Campaniform sensilla
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Campaniform sensilla monitor the forces generated by the leg muscles during the co-contraction phase of locust (Schistocerca gregaria) kicking and jumping and re-excite the fast extensor (FETi) and flexor tibiae motor neurones, which innervate the leg muscles. Sensory signals from a campaniform sensillum on the proximal tibia were compared in newly moulted locusts, which do not kick and jump, and mature locusts which readily kick and jump. The activity pattern of FETi during co-contraction was mimicked by stimulating the extensor tibiae muscle. Less force was generated and the spike frequency of the sensory neurone from the sensillum was significantly lower in newly moulted compared to mature locusts. Depolarisation of both FETi and flexor motor neurones as a result of sensory feedback was consequently less in newly moulted than in mature locusts. The difference in the depolarisation was greater than the decrease in the afferent spike frequency suggesting that the central connections of the afferents are modulated. The depolarisation could generate spikes in FETi and maintain flexor spikes in mature but not in newly moulted locusts. This indicates that feedback from the anterior campaniform sensillum comprises a significant component of the drive to both FETi and flexor activity during co-contraction in mature animals and that the changes in this feedback contribute to the developmental change in behaviour.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00222786
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  • 14
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    Electronic Resource
    Excitatory interactions between antagonistic motor neurones underlying locust kicking and jumping during maturation after the adult moult (1997)
    Springer
    Journal of comparative physiology 181 (1997), S. 231-237 
    Details
    ISSN: 1432-1351
    Keywords: Key words Motor pattern ; Motor neurone ; Insect ; Grasshopper ; Development ; Schistocerca gregaria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract There is a change in the synaptic connections between motor neurones that underlie locust kicking and jumping during maturation following the adult moult. The fast extensor tibiae (FETi) motor neurone makes monosynaptic excitatory connections with flexor tibiae motor neurones that have previously been implicated in maintaining flexor activity during the co-contraction phase of jumping, in which energy generated by the muscles of a hind leg is stored. The amplitude of the FETi spike decreases when repetitively activated, and this decrement is larger in locusts immediately following the adult moult than in mature locusts. The decrement in␣the FETi spike is correlated with a greater decrease in the amplitude of the flexor excitatory postsynaptic potential (EPSP) in newly moulted locusts and in turn with the failure of these locusts to kick or jump. The results presented here indicate that the developmental change in the connections between the motor neurones contributes to the change in behaviour following the moult.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003590050109
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  • 15
    Electronic Resource
    Electronic Resource
    Chick eye optics: zero to fourteen days (1996)
    Springer
    Journal of comparative physiology 179 (1996), S. 185-194 
    Details
    ISSN: 1432-1351
    Keywords: Chicks ; Refraction ; Development ; Schematic eye ; Ocular dimensions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Ocular dimensions and refractive state data for chicks 0 to 14 days of age were obtained from 234 untreated control eyes of birds treated unilaterally in previous work involving various defocussing lenses and/or translucent goggles. Refractive state and corneal curvatures were measured in vivo by retinoscopy and ophthalmometry respectively. Intraocular dimensions were measured by A-scan ultrasonography, after which the eyes were removed, weighed and measured. In some cases (n=52) intraocular dimensions and lens curvatures were obtained from frozen sections of enucleated eyes. The hyperopia of hatchling chicks (+6.5+4.0 D) initially decreases rapidly and then more gradually to + 2.0 ± 0.5 D by 16 days. The distribution of refractive errors is very broad at Day 0, but becomes leptokurtotic, with a slight myopic skew, by Day 14. Corneal radius is constant for the first four days, possible as a result of pre-hatching lid pressure, and then increases linearly, as do all lens dimensions, axial diameter and equatorial diameter. Schematic eyes were developed for Days 0, 7, and 14.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00222785
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  • 16
    Electronic Resource
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    Patterns of muscle activity during different behaviors in chicks: implications for neural control (1996)
    Springer
    Journal of comparative physiology 179 (1996), S. 169-184 
    Details
    ISSN: 1432-1351
    Keywords: Electromyogram ; Kinematics ; Development ; Chicken ; Locomotion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The large behavioral repertoire that spans the embryonic and postembryonic stages of development make chicks an ideal system for identifying patterns of muscle activity that are common to different behaviors and those that are behavior-specific. The main goal of this work was to identify the similar and dissimilar aspects of the recruitment patterns and the regulation of muscle activity during three distinct postembryonic behaviors: walking, swimming and airstepping. We identified two synergies that were common to each of these behaviors. The synergies were not disrupted by the absence of FT1 activity in airstepping. Within each synergy the recruitment time, recruitment order and duration of activity were not rigid, but varied according to the context-specific resistance that the leg encountered. Unlike the other muscles, FT2 activity was not recruited as part of the same synergy in each behavior. When weight-bearing contact with the substrate did not occur, as in swimming and airstepping, as well as in walking in chicks with deafferented legs, FT2 activity was not recruited as part of either synergy, but was recruited during the time between them. Although not identical, embryonic motility and hatching motor pattern both show the two synergies described for the postembryonic behaviors. Like the latter behaviors, the synergies tolerated the absence of activity from specific muscles. Thus, we suggest that the CNS produces different behaviors using many of the same muscles by organizing the patterned activity around two common synergies while permitting the different muscles that participate in a synergy to be modified in tandem or on an individual basis. Furthermore, the common synergies are established early during prenatal development in chicks.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00222784
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  • 17
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    Electronic Resource
    Uptake and metabolism of albumin by rodent incisor enamel In vivo and postmortem: Implications for control of mineralization by albumin (1994)
    Springer
    Calcified tissue international 55 (1994), S. 467-472 
    Details
    ISSN: 1432-0827
    Keywords: Enamel ; Development ; Albumin ; Mineralization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract The distribution of albumin throughout enamel development in the rat mandibular incisor was investigated using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS PAGE) and Western blotting employing an anti-rat albumin antibody. Intact albumin was detectable at all stages of enamel development but was most evident during late secretion/transition. Its concentration was subsequently reduced during the maturation stage. Albumin degradation products appeared during the transition/early maturation stage indicating that albumin breakdown preceded its removal. As albumin inhibits apatite crystal growth, its degradation and removal may be a necessary prerequisite for normal enamel crystal growth, perhaps reflecting a general mechanism for removal of residual endogenous matrix or adventitious crystal growth inhibitors. Additional studies revealed that the maturation stage was particularly susceptible to albumin influx postmortem. Albumin could therefore form part of the natural crystal growth control process, which, if not removed, could hamper maturation and lead to white spot hypoplasias.
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    Human amelogenesis I: High resolution electron microscopy study of ribbon-like crystals (1992)
    Springer
    Calcified tissue international 51 (1992), S. 259-268 
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    ISSN: 1432-0827
    Keywords: Human enamel ; Development ; Hydroxyapatite ; Structural defects ; High resolution electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Ribbon-like crystals, from developing enamel of human fetuses, were studied by high resolution electron microscopy. These crystals were classically described as the first organized mineral formed during amelogenesis. They were characterized by a mean width-to-thickness ratio (W.T-1) of 9.5, and 40% were bent. On lattice images we noted the presence of the central dark line (CDL) associated with white spots. Both structures were found in crystals with a minimum thickness of 8–10 nm. CDLs were localized in the center of the crystals and seemed to be linked to the initial growth process, but their exact structure and function were not fully determined. We were able to study the structure of the ribbon-like crystals with a Scherzer resolution close to 0.2 nm. The good correspondence between experimental and computed images showed that their structure was related to hydroxyapatite (HA). In addition, the presence of ionic substitutions and deficiencies were also compatible with HA. In this study, about 50% of the crystals showed structural defects. Screw dislocations were the most often noted defects and were observed within crystals aligned along five different zone axes. Low- and high-angle boundaries were also detected. Low-angle boundaries, found in the center of the crystals, could thus be related to CDLs and be implicated in the nucleation step of crystal formation, whereas high-angle boundaries could result from the fusion of ribbon-like crystals. Such mechanisms could induce an acceleration of the growth in thickness of the crystal observed during the maturation stage of amelogenesis.
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    Differential depolarization-activated calcium responses in fetal and neonatal rat osteoblast-like cells (1994)
    Springer
    Calcified tissue international 54 (1994), S. 278-283 
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    ISSN: 1432-0827
    Keywords: Calcium channels ; Development ; Osteoblastic cells ; Fura-2 ; Patch-clamp
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract The present study evaluates differential occurrence of voltage-dependent calcium channels (VDCC) in the membranes of fetal (FROB) and neonatal (NROB) calvarian rat osteoblastic cells in primary culture. The intracellular calcium concentration ([Ca2+]i) was monitored upon depolarization of the cell membrane with the use of high K+ containing extracellular solutions. [Ca2+]i was measured in populations of cells as well as in individual cells using Fura-2, whereas the membrane potential (Em) was recorded in parallel experiments using patch-clamp techniques. Increasing the extracellular K+ concentration resulted in an instantaneous depolarization of Em of both FROB and NROB. This depolarization of Em did not significantly affect [Ca2+]i of populations of FROB and neonatal osteoblast precursors (NpROB). In contrast to FROB and NpROB, NROB populations responded to depolarization with significant transient [Ca2+]i increases that could be blocked by the calcium antagonist verapamil and were absent if extracellular Na+ was replaced for choline instead of K+. In individual cell measurements, response frequencies as well as the magnitude of [Ca2+]i responses upon depolarization of NROB were much higher than those of FROB, suggesting that more NROB than FROB possess VDCC. This phenomenon might point to a development-related expression of VDCC in the membranes of osteoblast-like cells.
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    Naphthylamidase* in ameloblasts during enamel maturation (1971)
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    Calcified tissue international 7 (1971), S. 267-276 
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    ISSN: 1432-0827
    Keywords: Tech ; Development ; Enamel ; Enzyme ; Histochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé L'activité en naphtylamidase est étudiéc au niveau des incisives et molaires de rat, à divers stades de développement. Du L-leucyl-4-methoxy-2-naphtylamide, du L-alanyl-4-methoxy-2-naphtylamide, du L-leucyl-2-naphthylamide et du DL-alanyl-2-naphtylamide sont utilisés comme substrats: du bleu rapide B et du grenat rapide GBC sont employés comme sels de diazonium. Le naphtylamidase n'est pas visible au niveau de dents, en voie de dévelopment, au cours de la formation matricielle de l'émail. A la fin de ce stade, le naphtylamidase est présent au niveau de l'extrémité distale des améloblastes, près de la surface de l'émail. L'activité enzymatique reste identique jusqu'au moment de la fusion de l'épithélium dentaire et de l'épithélium buccal, au moment de l'éruption de la dent dans la cavité buccale. On ne rencontre pas de naphtylamidase au niveau d'autres tissues dentaires; cependant une activité marquée est observée dans les ostéoclastes au niveau des surfaces de résorption de l'os alvéolaire, entourant les dents, en voie de développement et d'éruption, et dans certaines régions du tissu conjonctif.
    Abstract: Zusammenfassung Die Aktivität der Naphthylamidase wurde in den Backen- und Schneidezähnen von Ratten in verschiedenen Entwicklungsstufen studiert. Als Substrate wurden L-leucyl-4-methoxy-2-naphthylamid, L-alanyl-4-methoxy-2-naphthylamid, L-leucyl-2-naphthylamid und DL-alanyl-2-naphthylamid verwendet; als Diazoniumsalze dienten Echtblau B und Echt-Granat GBC. Naphthylamidase konnte während der Schmelzmatrixbildung im Zahn nicht nachgewiesen werden. Nach Abschluß dieser Phase erschien Naphthylamidase in den distalen Enden der Ameloblasten, nahe bei der Schmelzoberfläche. Die Enzymtätigkeit blieb am selben Ort lokalisiert, bis das Zahnepithel, im Augenblick wo der Zahn in die Mundhöhle durchstößt, in das Mundepithel überging. Naphthylamidase wurde in anderen Zahngeweben nicht gefunden, aber eine deutliche Aktivität konnte in gewissen Bezirken des Bindegewebes sowie in den Osteoklasten der resorbierenden Oberflächen vom alveolären Knochen festgestellt werden, welcher die sich bildenden und die hervorstoßenden Zähne umgibt.
    Notes: Abstract Naphthylamidase activity was studied in rat molar and incisor teeth at different stages of development. L-leucyl-4-methoxy-2-naphthylamide, L-alanyl-4-methoxy-2-naphthylamide, L-leucyl-2-naphthylamide and DL-alanyl-2-naphthylamide were used as substrates and Fast blue B and Fast Garnet GBC as diazonium salts. Naphthylamidase was not demonstrable in the teeth during enamel matrix formation. After the termination of this stage, naphthylamidase was present in the ameloblasts in their distal ends close to the enamel surface. The enzyme activity retained this localization until the dental epithelium fused with the oral epithelium at the time of tooth eruption into the oral cavity. Naphthylamidase was not found in other dental tissues, but marked activity was found in osteoclasts at the resorbing surfaces of alveolar bone surrounding the developing and erupting teeth and in certain areas of the connective tissue.
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    Tetracycline effects on statolith and nematocyst differentiation inAurelia (1972)
    Springer
    Calcified tissue international 9 (1972), S. 122-130 
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    ISSN: 1432-0827
    Keywords: Tetracycline ; Development ; Calcification ; Statolith ; Nematocysts ; Aurelia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé L'effet de la tétracycline HCl sur la synthèse de statolithes de sulfate de calcium chezAurelia a été étudié. La tétracycline inhibe la synthèse de statolithes et nématocystes à un stade précoce de strobilation. La tétracycline, cependant, n'est pas incorporée dans les statolithes ou nématocystes en formation. Comme la tétracycline ne se combine pas avec le calcium des statolithes de sulfate de calcium dihydraté d'Aurelia, l'explication des effets d'inhibition sur la différenciation de statolithes et nématocystes ne semble pas liée avec un facteur en rapport avec l'incorporation. Des étudesin vitro de quatre systèmes inorganiques de calcium et de tétracycline montrent que le sulfate de calcium dihydraté (gypse) n'incorpore pas la tétracycline: il en est de même de son équivalent isostructural, le phosphate de calcium hydrogéné dihydraté (brushite). Le carbonate de calcium et le phosphate de calcium (apatite) incorpore la tétracycline. L'explication des différences de comportement du calcium peut être liée à la structure cristalline des composés respectifs, et, en particulier, au fait que l'ion Ca est prêt ou non à réagir avec la tétracycline.
    Abstract: Zusammenfassung Es wird über die Wirkung von Tetracyclinchlorhydrat auf die Synthese von Calciumsulfat-Statolithen beiAurelia berichtet. Wird das Tetracyclin in einem Frühstadium der Strobilation verabreicht, so hemmt es die Synthese der Statolithen und der Nematocysten. Das Tetracyclin wird jedoch nicht in die sich bildenden Statolithen oder Nematocysten eingebaut. Da sich das Tetracyclin nicht mit dem Calcium der Calciumsulfatdihydrat-Statolithen derAurelia verbindet, so kann dessen Hemmwirkung auf die Statolithen und die sich differenzierenden Nematocysten offenbar nicht mit einem einbaubedingten Faktor erklärt werden. Untersuchunge, die in vitro mit vier verschiedenen anorganischen Calciumsalzen und Tetracyclin ausgeführt wurden, zeigten, daß weder Calciumsulfatdihydrat (Gips), noch dessen isotrukturelles Aequivalent Calciumhydrogenphosphatdihydrat (Bruschit) Tetracyclin einbauen. Dagegen inkorporieren Calciumcarbonat und Calciumphosphat (Apatit) das Tetracyclin. Die Erklärung für dieses unterschiedliche Verhalten der Calciumsalze findet sich in der Kristallstruktur der betreffenden Verbindungen, d.h. es hängt davon ab, ob das Calciumion ür die Reaktion mit Tetracyclin leicht verfügbar ist.
    Notes: Abstract The effect of tetracycline HCl on synthesis of calcium sulphate statoliths inAurelia is reported. Tetracycline inhibits synthesis of statoliths and nematocysts when administered at an early stage of strobilation. The tetracycline, however, is not incorporated into the developing statoliths or nematocysts. As the tetracycline does not combine with the calcium of the calcium sulfate dihydrate statoliths ofAurelia, an explanation for its inhibitory effects on statoliths and nematocyst differentiation apparently does not rest with an incorporation-related factor. In vitro studies of four inorganic calcium systems and tetracycline revealed that calcium sulfate dihydrate (gypsum) did not incorporate tetracycline nor did its isostructural equivalent, calcium hydrogen phosphate dihydrate (brushite). Calcium carbonate and calcium phosphate (apatite) did incorporate tetracycline. The explanation for these different behaviors of calcium can be found in the crystal structure of the respective compounds, namely, whether or not the Ca ion is readily available to react with tetracycline.
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    Expression of parathyroid hormone-related protein in rat articular cartilage (1995)
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    Calcified tissue international 57 (1995), S. 196-200 
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    ISSN: 1432-0827
    Keywords: PTHrP ; Articular cartilage ; Chondrocyte ; Development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract Expression and localization of parathyroid hormone-related protein (PTHrP) in rat articular cartilage during fetal and postnatal periods were investigated by immunohistochemistry and in situ hybridization. PHTrP displayed distinct distribution and intensity of staining at different ages. In fetal (18-day-old) and young (3-week-old) rats, articular chondrocytes expressed abundant PTHrP throughout the entire thickness of cartilage. In contrast, in 60-week-old rats, PTHrP was expressed in a few articular chondrocytes of superficial and middle layers. Regulation of PTHrP and PTH/PTHrP receptor mRNA was also studied in cultured rat articular chondrocytes. Northern blot analysis revealed that both transforming growth factor-β (TGF-β), an important stimulator for chondrocyte proliferation and differentiation, and 10% fetal bovine serum (FBS) stimulated the expression of PTHrP mRNA with down-regulation of its receptor mRNA. In contrast, 12-O-tetradecanoylphorbol-13-acetate (TPA) down-regulated the expression of receptor without changes of PTHrP mRNA level. These results suggest that the changes in abundance and localization of PTHrP and its receptor may be directly involved in the cell growth and differentiation of articular cartilage.
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    URL: http://dx.doi.org/10.1007/BF00310258
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    Alkaline and acid phosphatase activities during growth of long bones and mandibles (1972)
    Springer
    Calcified tissue international 9 (1972), S. 173-178 
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    ISSN: 1432-0827
    Keywords: Phosphatase ; Development ; Bone ; Growth ; Rhythm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Une étude longitudinale, par séries, est effectuée pour déterminer les activités en phosphatases acide et alcaline dans les os longs et la mandibule. Le pH optimum des deux enzymes se situe respectivement à 10.2 et 5.4 pour les phosphatases alcaline et acide. Des portées synchronisées de rats sont sacrifiées, à raison d'une portée par jour, en commençant au premier jour jusqu'au 25ème jour post-partum. Les spécimens sont analysés en ce qui concerne leur concentration en protéine et leur activité en phosphatases. Une activité de types élevée et faible est observée au niveau du tissu osseux, ainsi qu'un type d'activité faible en phosphatase alcaline, au cours des pics d'activité en phosphatase acide, et vice-versa. Les pics observés suggèrent une concordance entre l'activité en phosphatase et les autres changements biochimiques de la croissance osseuse, au niveau de la matrice organique et la formation minérale. Une étude séparée, tenant compte de la possibilité d'une activité enzymatique rythmique, suggère l'existence d'un rythme diurne court chez les animaux jeunes.
    Abstract: Zusammenfassung Eine serienmäßige Longitudinaluntersuchung wurde unternommen, um die Aktivitäten der alkalischen und sauren Phosphatase in den Röhrenknochen und den Mandibulae von Ratten zu bestimmen. Das pH-Optimum der beiden Enzyme wurde für die alkalische Phosphatase bei 10,2 und für die saure Phosphatase bei 5,4 ermittelt. Synchronisierte und randomisierte Würfe wurden getötet, 1 Wurf pro Tag vom 1.–25. Tag post partum. Die Proben wurden auf ihren Proteingehalt und ihre Phosphatasenaktivität untersucht. Ein Muster niedriger und hoher Aktivität konnte in beiden Knochengeweben beobachtet werden, sowie ein Muster von niedriger Aktivität der alkalischen Phosphatase bei Spitzenwerten der sauren Phosphatase und umgekehrt. Die beobachteten Spitzenwerte lassen einen Zusammenhang vermuten zwischen der Phosphatasenaktivität und den anderen biochemischen Veränderungen, die im wachsenden Knochen auftreten, d. h. Bildung der organischen Matrix und des Minerals. Eine getrennte Untersuchung, welche sich mit der Möglichkeit rhythmischer Merkmale der Enzymaktivität befaßte, läßt vermuten, daß in den ersten Tagen ein schwacher Tagersrhythmus bestehen könnte.
    Notes: Abstract A serial longitudinal study was undertaken to determine the activities of the alkaline and acid phosphatases in the long bones and mandibles. The optimum pH of the two enzymes was recorded at 10.2 and 5.4 for alkaline and acid phosphatase, respectively. Synchronized and randomized litters of rats were killed, 1 litter daily, starting at day 1 to day 25 post partum. Samples were analyzed for protein concentration and activity of the phosphatases. A pattern of low and high activity was observed in both bony tissues, as well as a pattern of low alkaline phosphatase activity during acid phosphatase activity peaks, and vice versa. The observed peaks suggest a correspondence between phosphatase activity and the other biochemical changes occurring in the growing bone, i.e., organic matrix and mineral formation. A separate study, considering the possibility of rhythmic features of the enzyme activity suggests that there may be a small diurnal rhythm at an early age.
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    Structure and developmental expression of Ikaros in the Mexican axolotl (1999)
    Springer
    Immunogenetics 50 (1999), S. 336-343 
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    ISSN: 1432-1211
    Keywords: Key words Amphibian ; Axolotl ; Ikaros ; Hematopoiesis ; Development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  TheIkaros family of transcription factors plays an essential role in hematopoiesis. We report here the structure of cDNA clones encoding two Ikaros isoforms, Ik1 and Ik2, in the Mexican axolotl. The Ik1 cDNA sequence is very similar to that of the rainbow trout, chicken, and mammalian Ik1 sequences. However, a 96 base pair region which encodes the first N-terminal zing finger (F1) is lacking from axolotl Ik1, both in clones from a cDNA library and clones isolated from direct polymerase chain reaction products. A region corresponding to exon 3 is completely absent from the axolotl Ik2 sequence and thus the Ik1 and Ik2 isoforms possess the same number of zinc finger motifs. The structure of these five CC-HH motifs is very well conserved in the axolotl, including the structural deviations from its amino acid consensus composition which are identical in all species analyzed to date. The axolotl Ik1 3′ untranslated region sequence is very long (2538 bp) and contains two UA-rich motifs known as instability determinants and which could play a role in mRNA translational efficiency. Ikaros transcripts are first detected in the ventral blood island of stage 36 embryos, about 24 h before the first heartbeats (late tailbud stage), and then in the major lymphopoietic organs of the developing larvae. In situ hybridization demonstrates that Ikaros transcripts are abundant at the periphery of the thymus lobes, in the presumptive site of early thymocyte differentiation.
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    Wide tissue distribution of axolotl class II molecules occurs independently of thyroxin (1998)
    Springer
    Immunogenetics 47 (1998), S. 339-349 
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    ISSN: 1432-1211
    Keywords: Key words Axolotl ; Salamander ; Metamorphosis ; Development ; Class II
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  Unlike most salamanders, the Mexican axolotl (Ambystoma mexicanum) fails to produce enough thyroxin to undergo anatomical metamorphosis, although a “cryptic metamorphosis” involving a change from fetal to adult hemoglobins has been described. To understand to what extent the development of the axolotl hemopoietic system is linked to anatomical metamorphosis, we examined the appearance and thyroxin dependence of class II molecules on thymus, blood, and spleen cells, using both flow cytometry and biosynthetic labeling followed by immunoprecipitation. Class II molecules are present on B cells as early as 7 weeks after hatching, the first time analyzed. At this time, most thymocytes, all T cells, and all erythrocytes lack class II molecules, but first thymocytes at 17 weeks, then T cells at 22 weeks, and finally erythrocytes at 26–27 weeks virtually all bear class II molecules. Class II molecules and adult hemoglobin appear at roughly the same time in erythrocytes. These data are most easily explained by populations of class II-negative cells being replaced by populations of class II-positive cells, and they show that the hemopoietic system matures at a variety of times unrelated to the increase of thyroxin that drives anatomical metamorphosis. We found that administration of thyroxin during axolotl ontogeny does not accelerate or otherwise affect the acquisition of class II molecules, nor does administration of drugs that inhibit thyroxin (sodium perchlorate, thiourea, methimazole, and 1-methyl imidazole) retard or abolish this acquisition, suggesting that the programs for anatomical metamorphosis and some aspects of hemopoietic development are entirely separate.
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    A photosensitive circadian oscillator in an insect endocrine gland: photic induction of rhythmic steroidogenesis in vitro (1998)
    Springer
    Journal of comparative physiology 182 (1998), S. 343-349 
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    ISSN: 1432-1351
    Keywords: Key words Pacemaker ; Entrainment ; Ecdysteroids ; Prothoracicotropic hormone ; Development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The paired prothoracic glands of the insect Rhodnius prolixus each comprise a group of about 200 structurally identical cells. The synthesis (and release) of steroid moulting hormones (ecdysteroids) by these glands is under circadian control in vivo. We monitored ecdysteroid synthesis by single glands during long-term incubations in vitro. Synthesis is rhythmic in vitro and persists in continuous darkness. Glands which are arrhythmic (from prolonged continuous light) respond to transfer to darkness in vitro with the initiation of a free-running circadian rhythm of ecdysteroid synthesis. Therefore, the glands possess a light-sensitive circadian oscillator. These properties are conventionally associated with nervous tissue of animals. It is suggested that rhythmicity is synchronized within the gland by the known structural and electrical coupling between its component cells. The glands share properties with known pacemakers such as the avian pineal. However, the glands in vivo receive input from both light cues and the cerebral neuropeptide, prothoracicotropic hormone. Rhythmic release of this neuropeptide is controlled by a second oscillator located in the brain. We conclude that the pacemaker in the endocrine system of R. prolixus comprises at least three oscillators, one in each prothoracic gland and one in the brain, which are coupled hormonally. We conclude that the prothoracic gland is an important component of the circadian system controlling development in R. prolixus and that peripheral endocrine glands may play a more active role in the generation of animal circadian organization than has been thought.
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    Postembryonic development of mating behavior in the male cricket Gryllus bimaculatus DeGeer (1990)
    Springer
    Journal of comparative physiology 166 (1990), S. 775-784 
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    ISSN: 1432-1351
    Keywords: Mating behavior ; Development ; Insect nymph ; Cricket ; Decerebration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The intact male nymph cricket, Gryllus bimaculatus DeGeer, was found to show mating-like behavior, that is, courtship-like behavior (CSLB) and copulation-like behavior (CPLB), in the 7th and 8th (last) instars. The 8th instar nymph exhibited less CSLB and CPLB than the adult but much more than the 7th instar nymph. The movement patterns of CSLB and CPLB were essentially the same as those of adults except for motor acts requiring the use of the genitalia. CSLB was short and often ceased spontaneously before it switched to CPLB. CPLB also ended earlier than in adults. The occurrence of CSLB and CPLB was almost zero the few days around ecdysis. The nymph was very sensitive to disturbance, so that he often stopped courtship for more than 30 min after stimulation. CSLB was similarly induced in the male nymph (8th instar) by pairing with a female adult, male adult, female nymph (8th) and male nymph (8th). The female nymph (8th) was observed to mount not only the male adult but also the male nymph (8th). A fixed time sexual refractoriness forming a basis of cyclical mating activity was not present after CPLB in the nymph. It appeared in association with the emergence of spermatophore protrusion behavior around day 3 after the imaginal molt. In fledglings, there were some transitions during the sexual maturation process, such as failures in hook hanging, spermatophore extrusion, and spermatophore transfer to the female. The decerebration experiments on nymphs and fresh adults agreed with behavioral observations. These results suggest that the development of mating behavior in the male cricket is a process of enhancement of basic motor patterns but not a process of addition of new movements by changes in pattern generation circuits in the central nervous system.
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    Evoked pre- and post-synaptic activity in the optic tectum of the cannulated tadpole (1990)
    Springer
    Journal of comparative physiology 167 (1990), S. 377-390 
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    ISSN: 1432-1351
    Keywords: Visual system ; Rana pipiens ; Development ; Pharmacology ; Retinal afferents
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary We describe the cannulated Rana pipiens, tadpole preparation that allows for stable recording in the tectum of the extracellular potential elicited by optic nerve stimulation. The largest components of the evoked tectal response consist of two previously identified waves and a major third, long-latency wave of long duration. These components were reversibly eleminated by perfusion of high magnesium/no calcium Ringer's solution or Ringer's solution containing cobalt chloride. In contrast, perfusion of high calcium/no magnesium Ringer's increased the amplitude and area of these components. We conclude that these components represent post-synaptic activity. Additionally, small, short-duration waves were identified as arising from the activity of retinal afferents. They consisted of a short-latency (3.1–7.6 ms) and a long-latency (12–23 ms) group. Waves belonging to both of these classes were still visible in both high magnesium/ no calcium Ringer's solution or Ringer's solution containing cobalt chloride and were unaffected by high calcium/no magnesium Ringer's. The average conduction velocities of the short- and long-latency groups matched the conduction velocities of, respectively, edge and convexity detectors in the adult. This indicates that retinal afferent input may already be present in adult patterns at the time that tectal circuitry is developing.
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    Developmental attenuation of the pre-ecdysis motor pattern in the tobacco hornworm, Manduca sexta (1991)
    Springer
    Journal of comparative physiology 168 (1991), S. 179-190 
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    ISSN: 1432-1351
    Keywords: Motor program ; Manduca sexta ; Development ; Motoneuron ; Metamorphosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary At the culmination of each molt, the larval tobacco hornworm exhibits a pre-ecdysis behavior prior to shedding its old cuticle at ecdysis. Both pre-ecdysis and ecdysis behaviors are triggered by the peptide, eclosion hormone (EH). Pre-ecdysis behavior consists of rhythmic abdominal compressions that loosen the old larval cuticle. This behavior is robust at larval molts, but at the larval-pupal molt the only comparable behavior consists of rhythmic dorso-ventral flexions of the anterior body. These flexions appear to be an attenuated version of the larval pre-ecdysis behavior because (1) they show the same EH dependence, and (2) the motor patterns recorded from EH treated, deafferented larval and pupal preparations are similar except that the pupal pattern is much weaker. Both patterns are characterized by rhythmic, synaptically-driven bursts of action potentials in motoneurons MN-2 and MN-3, which occur synchronously in all segments. However, the synaptic drive to the motoneurons and their resultant levels of activity are reduced during the pupal pre-ecdysis motor pattern, especially in posterior abdominal segments. Although the dendritic arbors of both motoneurons regress somewhat during the larval-pupal transformation, this does not appear to be the primary source of diminished synaptic drive because regression is greatest in the segments in which synaptic inputs remain the strongest. The developmental weakening of the pre-ecdysis motor pattern thus may be due to changes at the interneuronal level.
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    The refractive development of the eye of the American kestrel (Falco sparverius): a new avian model (1992)
    Springer
    Journal of comparative physiology 170 (1992), S. 565-574 
    Details
    ISSN: 1432-1351
    Keywords: Eye ; Refractive error ; Development ; Kestrel ; Myopia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Most measures of avian visual performance are carried out on commonly available domestic species such as the chicken, and most of the data on avian induced refractive error deals with chickens. Raptors are predatory birds in which good visual resolving ability is particularly important. Behavioral studies indicate that the eyes of raptors have two to three times the resolving ability of the human eye. The domestic chicken is precocial at hatching whereas most raptors are semi-altricial. This study was an effort to determine if the effect of early visual deprivation on the refractive development of the chicken eye can be reproduced in the American kestrel, a species which is not domesticated and in which the need for acute vision is particularly important. Visual deprivation was achieved by unilaterally applying translucent plastic goggles over the eyes of kestrels two days after hatching. Refractive error was measured using a retinoscope and trial lenses. Ocular growth was monitored by A-scan ultrasonography, and frozen ocular sections of sacrificed birds. The effect of the experimental manipulation on the contralateral control eye and body weight was evaluated each day over a 42-day period. The goggles did not significantly affect the normal changes in body weight or the normal pattern of ocular growth and refractive development in the untreated eyes. An analysis of the refractive state changes as a result of form deprivation was made each week for 6 weeks after hatching on both the treated and untreated eyes in a separate group of experimental birds. Visual form deprivation caused a significant myopic shift in refractive error and a significant increase in the vitreous chamber depth in the treated eyes at 3 and 6 weeks of age. However, the amount of myopia produced is much less than that induced in chicks, and in certain cases hyperopia is produced. The kestrels recover from myopia and hyperopia within 10 days of goggle removal, after 3 to 4 weeks of deprivation. This study is the first indication that chickens may not be a representative bird model for studying form deprivation myopia. First, myopia is not always produced in kestrels in response to form deprivation. Second, kestrels are severely myopic at hatching and therefore, the direction of emmetropization is opposite to that found in hatchling chicks.
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    Etudes sur l'épicuticule des insectes (1970)
    Springer
    Cell & tissue research 108 (1970), S. 380-396 
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    ISSN: 1432-0878
    Keywords: Epicuticle ; Insects ; Tenebrio molitor ; Development ; Structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Résumé L'épicuticule de l'adulte de Tenebrio molitor est composée de deux couches distinctes dénommées épicuticule externe et épicuticule interne. L'épicuticule externe est la première couche cuticulaire sécrétée sous forme de petites plaques s'agrandissant par leurs bords pour recouvrir toute la surface cellulaire. Au moment de sa sécrétion, cette couche est formée de quatre lames denses A, B, C1 et C2. La lame B, très fine, disparaît par la suite et les lames C1 et C2 deviennent très nettes. L'épicuticule externe de l'adulte est donc formée de trois lames denses séparées par deux lames claires. L'épicuticule interne est formée de lames superposées denses et claires de structure complexe, qui sont masquées pendant la sécrétion des premières couches de cuticule lamellée (procuticule). Cette structure correspond à un arrangement moléculaire hautement organisé. La forme de la surface cuticulaire des sternites est déterminée par la forme de la surface cellulaire avant le dépôt de l'épicuticule.
    Notes: Summary The epicuticle of adult Tenebrio consists of two distinct layers named outer and inner epicuticle. The outer epicuticle is the first cuticular layer to be deposited in form of small patches on top of the microvilli. These initial patches are composed of four dense laminae (A, B, C1 and C2) separated by three light spaces. The outer epicuticle grows by densification of diffuse material at the edges of the patches until the entire area is covered. The thickness of outer epicuticle remains constant (175 Å) during the development of the pharate adult, lamina B however rapidly disappears. Thus, the adult outer epicuticle is fivelayered (three dense laminae: A, C1 and C2). After being deposited, the inner epicuticle shows a complex laminar structure interpreted to represent a highly organized molecular system. The laminae are masked during the formation of the first procuticle lamellae. During the deposition of the epicuticle, lamina A is covered by a component of the moulting fluid, forming an irregular dense layer which disappears after the resorption of this fluid. Perhaps this layer protects the new epicuticle from lytic enzymes of the moulting fluid. In adult animals, there is an additional superficial layer, the signification of which is not clear. The possibility of remains of cement or wax is discussed. The development of the surface patterns of the sternal and pleural cuticle is determined before the epicuticle formation by the shape of the epidermal surface. The rate of outer epicuticle deposition appears to depend on the size of the microvilli: epicuticle deposition seems to proceed faster over high microvilli.
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    The fine structure and development of the seminal vesicles and prostate in the fetal rat (1970)
    Springer
    Cell & tissue research 109 (1970), S. 1-14 
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    ISSN: 1432-0878
    Keywords: Seminal vesicle ; Prostate ; Fetal rat ; Ultrastructure ; Development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The development of the seminal vesicle from the Wolffian duct and of the prostate from the urogenital sinus has been studied in rat fetuses from day 14 of gestation to birth with the use of the electron microscope. Prior to the onset of androgen secretion, the cells of the urogenital sinus and the caudal part of the Wolffian duct have a simple undifferentiated appearance. After the onset of androgen secretion by the fetal testes at day 15, “intracytoplasmic confronting cisternae” of the granular reticulum appear in both urogenital sinus and Wolffian duct. Portions of the granular endoplasmic reticulum of the urogenital sinus become distended with a finely granular, moderately dense material. In the urogenital sinus, many hemidesmosomes are formed at the basal surface of the epithelium. Specializations of the extracellular materials are present opposite the hemidesmosomes. The formation of the seminal vesicles and the prostate begins at day 18–19 of gestation. The cells of the seminal vesicle are taller than the Wolffian duct cells from which they arise, the granular endoplasmic reticulum increases moderately in amount, and a patent lumen is formed. The cells of the fetal prostate do not differ greatly from those of the urogenital sinus from which they arise except that the prostatic cells initially lack hemidesmosomes. The fine structural changes are discussed in relation to the onset of fetal androgen secretion, the formation of the organs, and the functions of the cells in adult life.
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    URL: http://dx.doi.org/10.1007/BF00364926
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    Die morphologische Differenzierung des visceralen Blattes der Bowmanschen Kapsel (1970)
    Springer
    Cell & tissue research 111 (1970), S. 346-363 
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    ISSN: 1432-0878
    Keywords: Kidney ; Glomerulus ; Development ; Scanning electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Die Differenzierung der Podocyten wurde an Nieren 10 Tage alter Ratten raster-elektronenmikroskopisch untersucht und mit durchstrahlungs-elektronenmikroskopischen Befunden verglichen. Die Podocytenfortsätze können danach auf dreierlei Wegen gebildet werden: 1. Spalten innerhalb des Cytoplasmas lassen bandartige Cytoplasmabrücken entstehen. Diese gliedern sich weiter auf, bis zahlreiche miteinander verzahnte Fortsätze derselben Zelle entstanden sind. 2. Vom Zellrand her werden dicke Fortsätze weit vorgeschoben, die kleinere Fortsätze bilden. Durch sie können Verzahnungen mit entfernten Deckzellen entstehen. Die kleinen Fortsätze können sich jedoch auch mit anderen Fortsätzen der eigenen Zelle verzahnen. 3. Fingerförmige Fortsätze benachbarter Zellen verzahnen sich während ihrer Entstehung miteinander. Trotz zahlreicher desmosomenartiger Haftstellen zwischen benachbarten Podocyten entwickeln sich ihre Fortsätze und deren Verzahnungen anscheinend weitgehend autonom und nur selten nach den vermuteten Regeln epithelialer Nachbarschaft (Typ 3). Die Befunde sprechen vielmehr dafür, daß durchflutete und wachsende Glomerulumkapillaren die Podocytendifferenzierung induzieren und die Orientierung der Fortsätze beeinflussen.
    Notes: Summary The differentiation of the podocytes was studied by scanning electron microscopy on kidneys of 10 days old rats. The results were compared with transmission electron microscopic pictures from the same kidneys. There are three ways of forming processes by the podocytes: 1. Slits within the cytoplasm give rise to cytoplasmic bridges which further divide themselves and finally build up a meshwork of processes within a cell. 2. Thick and sometimes very long processes originate from the cell border. Their smaller branches may interdigitate with those of distant podocytes or with other processes out of the same cell. 3. Finger-like processes of neighbouring cells interdigitate as soon as they develop. In spite of numerous desmosomal structures between neighbouring podocytes the cell processes and their interdigitations develop mostly independently from each other and only seldom after the expected rules of epithelial vicinity (type 3). These findings are interpreted as indication that flooded and growing capillaries induce the differentiation of podocytes and that they influence the orientation of their processes.
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    The structure of the terminal sensilla on the maxillary palps of Locusta migratoria (L.), and changes associated with moulting (1971)
    Springer
    Cell & tissue research 121 (1971), S. 48-68 
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    ISSN: 1432-0878
    Keywords: Chemoreceptor ; Locusta ; Fine structure ; Development ; Moulting
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The basic structure of the terminal sensilla of Locusta migratoria resembles that of Schistocerca gregaria. There are commonly six or ten neurons whose dendrites extend almost to the opening of the peg. Proximally the dendrites are clothed by a neurilemma cell which also encloses a basal cavity through which their ciliary region passes. The tormogen cell encloses the receptor-lymph cavity and actively secretes material into it. The receptor-lymph cavity and the basal cavity are quite separate. The development of new pegs at a moult is described. After apolysis the scolopale extends across the subcuticular space and protects the dendrites, which remain in a functional condition until shortly before ecdysis. As the trichogen cell grows out to form a new peg the tip is surrounded by a mass of electron-dense material, probably derived from the receptorlymph cavity. The function of this material is unknown. Regeneration of the dendrites is considered. The possible mechanism by which the tip of the peg opens and closes is considered and the general structure of the organule is discussed in relation to functioning.
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    Interrelationship of renal vascular development and nephrogenesis (1994)
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    Cell & tissue research 277 (1994), S. 247-257 
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    ISSN: 1432-0878
    Keywords: Key words: Kidney ; Vascular system ; Development ; ontogenetic ; Vasculogenesis ; Endothelium-dectecting antibodies ; Rabbit
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. Within the cortex region of the neonatal rabbit kidney the developing microvasculature was investigated by means of two endothelium-detecting antibodies (EnPo 1 and EC1). Rows of antibody-labelled cells were found within tissue regions that had previously been described as avascular. We conclude that these vessel-like structures detected by EnPo 1 and EC1 are capillary precursors without lumina. Furthermore, beneath the fibrous capsule within the morphologically homogeneous mesenchyme two cell populations can be discriminated by use of differential antigen expression. The EnPo 1 antigen, which is abundant on endothelial cells and podocytes at different developmental stages, was detected on a subpopulation of mesenchymal cells. These cells were exclusively detected surrounding the tip of the collecting duct ampulla. Due to the unique specificity of EC1 and EnPo 1 the process of microvascular development can be readily followed on serial optical sections gained by laser scan microscopy. (1) Adjacent to EnPo 1-positive mesenchymal cell islets vessel-like structures are found that are in contact with the differentiated vasculature. (2) The renal vesicle is enclosed by a network of vessel-like structures establishing contact with differentiated vessels. (3) No guidance of invading capillary sprouts toward the developing glomerulus and nephron is required, since vascular elements already accompany the earliest detectable nephron stage.
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    BMP/GDF-signalling interactions during synovial joint development (1999)
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    Cell & tissue research 296 (1999), S. 111-119 
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    ISSN: 1432-0878
    Keywords: Key words Synovial joint ; Development ; Hyaluronan ; BMP ; GDF-5 ; Antagonists
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The synovial joint arises from an initial condensation of cells that subsequently develops into distinct skeletal structures, separated by the joint. Bone morphogenetic proteins (BMPs) and growth and differentiation factors (GDFs) have a fundamental role during skeletogenesis, including joint formation. Development of the joint appears to be dependent on the differential expression/activity of the related BMP and GDF subfamilies. Gdf-5 is expressed in the developing joints and is necessary for the formation of some joints. In contrast, recent data has shown that antagonism of the BMP family is crucial for joint formation. Here, we review mechanisms of how BMP signalling may be antagonised/modified. We also describe the expression of Bmp-2 and Bmp-4 together with two BMP antagonists, chordin and noggin, during chick joint development. Finally, we discuss possible mechanisms of how a joint forms and the evidence that the joint is a ’signalling centre’ that may coordinate the development of adjacent skeletal structures.
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    A comparison of the fine structure of thoracic and abdominal interganglionic connectives in the newly hatched and adult stick insect, Carausius morosus Br. (1973)
    Springer
    Cell & tissue research 145 (1973), S. 299-309 
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    ISSN: 1432-0878
    Keywords: Nervous system ; Stick insect ; Blood-brain barrier ; Development ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The fat body sheath which surrounds the ventral nerve cord of the adult stick insect, Carausius morosus, is absent in the hatchling. Since the haemolymph sodium ion compositions of the two stages are similar, it is suggested that the fat body sheath is not a site of a blood-brain barrier dealing with extra-axonal regulation of sodium. Similarities of ultrastructure in connectives of adults and hatchlings are demonstrated, and tight junctions are shown to occur in perineural cells of both stages. The possible significance of this to the blood-brain barrier of this insect is discussed.
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    URL: http://dx.doi.org/10.1007/BF00307160
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    Untersuchungen über die Ultrastruktur der Gonaden von Chironomus (Dipt.) (1970)
    Springer
    Cell & tissue research 106 (1970), S. 348-370 
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    ISSN: 1432-0878
    Keywords: Ovary ; Insect ; Chironomus ; Development ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Im Ovar von Chironomus sind in Phase 1 des 4. Larvenstadiums polygonal abgeflachte „Innenzellen“ von kleineren „Außenzellen“ umgeben, die Bakteroide und Phagosomen enthalten; zwischen den Innenzellen liegen unregelmäßige Zelltrümmer („keimbahnbegleitende Substanzen“). Zu Beginn der Ovariolenbildung werden in Phase 3 durch Spalträume zwei Schichten der Außenzellen voneinander getrennt, von denen die innere (Follikel- und Eikanalepithel) regelmäßige Buchten bildet. In diese Buchten wandern von innen Zellpaare ein, die an „synaptischen Komplexen“ bzw. multiplen Chromatinstrukturen als Ei- und Nährzellen kenntlich sind. Zwischen beiden Zellen sind „Fusome“ häufig, die später in eigentümlicher Weise geschlossen werden. Zwischen den Eikanalzellen entsteht in Phase 5 durch Spaltbildung der Eikanal; in Phase 7 sind die Eikanalzellen auffallend glykogenreich. Kurz vor der Vitellogenese treten im Bereich der Oocyte Membransysteme und „annulated lamellae“ auf; akzessorische Kerne werden als Ausstülpungen des Oocytenkernes gebildet und später abgeschnürt. In Phase 9 sind an der Peripherie der Eizelle Mikrovillisäume und Pinocytosebläschen sichtbar. Die distalen Zellen der Ovariole haben Eioder Nährzellcharakter, sind aber bei Ch. melanotus nicht von Follikelzellen umgeben und werden beim weiteren Ovariolenwachstum reduziert. Trotz extrem geringer Nährzellzahl der Follikel scheint das Chironomus-Ovar funktionell nicht von anderen polytroph meroistischen Insektenovarien unterschieden.
    Notes: Summary In the ovary of Chironomus during phase 1 of the fourth larval instar, polygonally flattened “inner cells” are surrounded by smaller “outer cells” which contain bacteroids and phagosomes. Irregular cell remnants (“germ line accompanying substances”) lie among the inner cells. At the beginning of ovariole formation in phase 3, two layers of outer cells are separated by the formation of fissures. The inner layer of these cells (follicle- and egg-passage epithelium) forms regular invaginations. Cell pairs, identified as oocytes and nurse cells by “synaptic complexes” or multiple chromatin structures, wander from inside into the invaginations. Frequently between the two cells are fusomes, which later close in a characteristic manner. During phase 5, an egg passage is formed as a fissure among the egg-passage cells. During phase 7, the egg passage cells are conspicuously full of glycogen. Shortly before vitellogenesis membrane systems and annulated lamellae appear in the region of the oocyte. Accessory nuclei are formed by a “tieing-off” of projections of the the oocyte nucleus. During phase 9, microvilli and pinocytotic vesicles can be seen at the periphery of the oocyte. The distal cells of the ovariole are of oocyte or nurse cell nature, but in Ch. melanotus they are not surrounded by follicle cells and are reduced during further ovariole growth. In spite of the extremely small number of nurse cells in the follicle, the Chironomus ovary apparently does not differ functionally from other polytrophic meroistic insect ovaries.
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    Studies on the effect of denervation in developing muscle (1973)
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    Cell & tissue research 147 (1973), S. 75-85 
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    ISSN: 1432-0878
    Keywords: Skeletal muscle ; Denervation ; Development ; Fiber types, myofibrils ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Ultrastructural diversification of muscle fibers, with regard particularly to myofibrillar changes, has been investigated in the fast-twitch extensor digitorum longus (EDL) and the slow-twitch soleus muscles of the rat during fetal and postnatal development in the presence and in the absence of motor innervation. The band pattern and the shape of the myofibrils were uniform in fetal and neonatal muscle fibers and underwent differential changes during the first weeks after birth, concomitantly with fiber type specialization. The most evident variations in myofibrillar structure arising in this period concern the thickness of the Z band and the arrangement of the myofibrils. Myofibril formation was at first not impaired by denervation of rat muscles performed in utero and, although focal disintegration of myofibrils and detachment and loss of orientation of filaments became apparent by one week, atrophic muscle fibers with well-organized myofibrils could be seen as late as 2 months after birth. However, denervated muscle fibers of EDL and soleus did not display any significant and consistent difference in myofibrillar band pattern and shape. No variation in mitochondrial content and sarcoplasmic reticulum development was likewise seen in muscle fibers of EDL and soleus after fetal denervation. The findings emphasize the importance of neuromuscular interactions in muscle differentiation.
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    Structure and development of the tracheal organ in the mesothoracic leg of the cricket Teleogryllus commodus (Walker) (1974)
    Springer
    Cell & tissue research 147 (1974), S. 325-334 
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    ISSN: 1432-0878
    Keywords: Chordotonal (Tracheal) organ ; Teleogryllus commodus (Orthoptera) ; Hearing ; Development ; Structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The tracheal organ of the mesothoracic tibia of Teleogryllus is located in a corresponding position to the tympanal organ of the prothoracic tibia. The mesothoracic organ contains an average of only 12 scolopidia, the location of which corresponds to that of the proximal group A and proximal main group in the prothoracid tympanal organ. There are no scolopidia corresponding to the distal group of the tympanal organ. The variability in number of scolopidia is much greater in the mesothoracic organ than in the prothoracic organ. The adult tracheal system of the mesothoracic leg resembles the early nymphal tracheal system in both pro- and meso-thoracic legs. The development of the tracheal organ is usually complete by the sixth instar. The mesothoracic tracheal organ of the adult is broadly equivalent to the prothoracic tympanal organ of a fifth instar animal.
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    Ultrastructure of synaptosomes from one-day old and adult rat brain stem (1974)
    Springer
    Cell & tissue research 148 (1974), S. 535-550 
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    ISSN: 1432-0878
    Keywords: Synaptosomes ; Rat brain stem ; Synaptogenesis ; Development ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructure and protein content of the five subfractions of the crude mitochondrial fraction from the brain stem of the 1-day old and adult rat was examined. The morphological composition of the subfractions after fixation in glutaraldehyde and osmiumtetroxide in the adult rat brain stem resembled that previously reported for the whole brain; synaptosomes sedimented in a sucrose gradient in subfractions C and D. In the 1-day old rat, mature synaptosomes were found in subfractions A, B, C and D; E contained mainly free mitochondria. 80–95% of the processes in the adult and 10–30% in the 1-day old rat contained synaptic vesicles which were of four types: (1) small agranular vesicles (2) large dense core vesicles (3) large agranular vesicles (4) coated vesicles. Pre- and postsynaptic membrane thickenings were demonstrated in many nerve-ending particles. In the subfractions of the 1-day old rat the protein content was one half and the distribution resembled that in the adult. Evidently nerve endings develop faster in the brain stem than in cortical areas; a serotoninor adrenergic origin of the early synaptosomes is suggested.
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    Development of muscle spindles deprived of fusimotor innervation (1973)
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    Cell & tissue research 144 (1973), S. 435-452 
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    ISSN: 1432-0878
    Keywords: Muscle spindles ; Intrafusal fibre types ; Development ; Deefferentation ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Muscle spindles of limb muscles were deefferented in neonatal rats by sectioning ventral roots or by removal of the lumbosacral spinal cord. Ten to 56 days after the operation, muscle spindles were examined in the medial gastrocnemius, extensor digitorum longus and soleus muscles. The differentiation of muscle spindles was not affected by deefferentation. The number of spindles in the investigated muscles was not reduced. Intrafusal fibres increased in number from two at birth to four per spindle on the average, as in normal muscles. The characteristic ultrastructural distinctions of nuclear bag and nuclear chain fibres developed as under normal conditions. However, intrafusal fibres atrophied slowly after fusimotor denervation, their polar zones becoming reduced in diameter by about 25% in comparison with control fibre diameters. Spindle capsules, on the other hand, increased in size and attained diameters comparable with normal spindles, appearing even somewhat distended. As intrafusal fibres degenerate after complete denervation at birth (Zelená, 1957), but differentiate in the absence of fusimotor innervation, it can be concluded that sensory nerve terminals induce and support their development. It is assumed that the morphogenetic influence of sensory terminals is mediated by release and uptake of a trophic substance at the synaptic junction. The occurrence of light and dense core vesicles in the sensory terminals and of coated invaginations and vesicles at both the axonal and plasma membrane speak in favour of such a possibility.
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    Acinar ultrastructure of the submandibular gland of Mus musculus during embryonic development (1974)
    Springer
    Cell & tissue research 150 (1974), S. 425-442 
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    ISSN: 1432-0878
    Keywords: Glandula submandibularis (Mouse) ; Acinar ultrastructure ; Cell types ; Development ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The development of the submandibular gland of the mouse was studied by means of electron microscopy, from the 14th day of gestation up to birth. In the first two days the acini are solid and their cells contain polyribosomes and a few lamellae of endoplasmic reticulum. Beginning with the 16th day secretory granules appear and rapidly fill an increasing number of cells. The different electron density of the granules makes it possible to distinguish 1. two types of granules, dense and pale, and sometimes intermediate ones, 2. “polymorphic” granules. The latter consists of electron dense and electron pale parts combined in different configurations. The possible significance of the various types of granules is discussed.
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    Studies on the juxtaglomerular apparatus (1974)
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    Cell & tissue research 151 (1974), S. 433-456 
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    ISSN: 1432-0878
    Keywords: Juxtaglomerular apparatus (Rat) ; Development ; Renin ; Pools ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Die perinatale Entwicklung des juxtaglomerulären Apparates, insbesondere das Verhalten der epitheloiden Zellen wurde an 18 trächtigen Ratten and 65 Embryonen bzw. Jungtieren elektronenmikroskopisch untersucht. Parallel dazu wurde die Reninkonzentration bzw. der Reningehalt bestimmt. Spezifische Sekretgranula finden sich erstmals am 18. Tag der Fetalzeit, und zwar in den epitheloiden Zellen des juxtaglomerulären Apparates juxtamedullärer Nephrone. Die Granula machen einen Struktur- und wahrscheinlich auch Funktionswandel durch, der eine Einteilung in drei verschiedene Granulatypen nahelegt. Diesen drei Typen spezifischer (reninhaltiger) Sekretgranula werden die Lysosomen als unspezifische Einschlüsse der epitheloiden Zellen gegenübergestellt. Im einzelnen kommt es während der perinatalen Phase in den fetalen Epitheloidzellen zuerst, d.h. pränatal, zu einer Hypertrophie des rauhwandigen endoplasmatischen Retikulums und des Golgi-Apparates. Hierin sehen die Autoren einen Hinweis auf eine erhöhte Proteinsynthese mit entsprechender Zunahme der Transport- und Konzentrationsvorgänge. Nach der Geburt findet sich dann auch eine deutliche Zunahme der Sekretgranula vom Typ III, die als reife Reningranula (mature granules) angesehen werden. Die bisher noch nicht beschriebenen kleinen Sekretgranula vom Typ I dagegen kommen in weniger entwickelten Epitheloidzellen häufiger vor. Bestimmungen der Reninverteilung zwischen Zytoplasma und den durch Differential-zentrifugation gewonnenen Granula-Fraktionen ergeben auffallende Parallelen zu den morphologischen Befunden. Diese sprechen im allgemeinen dafür, daß “freies Renin” im Ergasto-plasma und “gebundenes Renin” in den Sekretgranula vorliegt. Mit zunehmendem Alter scheint es außerdem — parallel zur relativen Abnahme des Ergastoplasmas und Zunahme der reifen Reningranula — zu einer Verminderung des extragranulären zugunsten des granulär gebundenen Renins zu kommen.
    Notes: Summary The perinatal development of the Juxtaglomerular apparatus (JGA), with particular reference to the epithelioid cells, was studied. Electron microscopic studies were carried out on 18 gravid rats and 65 embryos with corresponding determinations of renin concentration and the renin contents by bio-assay. Specific secretory granules of the epithelioid cells of the JGA of juxtamedullary nephrons are first observed on the 18th day of gestation. The classification into three types of secretory granules suggests that they undergo a structural and probably also a functional transformation. All three types of secretory granule may be regarded as specific, renin-containing, cytoplasmic organelles. During the last days of gestation, the rough-surfaced endoplasmic reticulum and the Golgi apparatus become hypertrophied in epithelioid cells, indicating an increased protein synthesis as well as transport and concentration processes. After birth, there is a definite increase in the number of Type III secretory granules-which may be regarded as mature granules. The small Type I secretory granulesnot previously described-are found more frequently in the immature epithelioid cells. Determinations of the renin distribution in the plasma and in fractions of cytoplasmic constituents (total homogenate, secretory granules) prepared by differential centrifugation showed striking congruence with the morphological findings. It is generally assumed that “soluble renin” occurs in the endoplasmic reticulum and “bound renin” in secretory granules. A shift from extragranular to granular (bound) renin, occurs with increasing age, having its morphological equivalent in the relative decrease of the endoplasmic reticulum and increase in mature secretory granules.
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    The differentiation of intrafusal fibre types in rat muscle spindles after motor denervation (1974)
    Springer
    Cell & tissue research 153 (1974), S. 115-136 
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    ISSN: 1432-0878
    Keywords: Muscle spindles ; Intrafusal fibre types ; Development ; De-efferentation ; Utrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Hind limb muscles were de-efferented in 19 new-born rats by removal of the lumbosacral spinal cord, with preservation of spinal ganglia and their peripheral branches. The juxtaequatorial and polar zones of muscle spindles were studied in different leg muscles 3 to 9 weeks after the operation in order to establish whether intrafusal fibre types would become differentiated after permanent motor denervation. De-efferented intrafusal fibres developed into distinct ultrastructural fibre types similar to those found in control muscles. The nuclear bag type had confluent myofibrils with ill-defined M lines and relatively few mitochondria. The nuclear chain type had discrete myofibrils with prominent M lines, numerous large mitochondria and a more developed sarcotubular system. The fibre type characteristics were sometimes blurred by disarranged cross striation, but they were clearly discernible in 59 out of 69 de-efferented fibres of 31 spindles investigated in the electron microscope. A sample of 220 de-efferented spindles from leg muscles of 6 rats was examined in the light microscope on transverse sections stained for ATPase activity. The difference in the ATPase activity among intrafusal fibre types was marked in about 70% spindles; in contrast to this, no distinct fibre types could be discerned in the population of extrafusal fibres which were stained rather uniformly. In de—efferented spindles-as in normal control spindlesnuclear chain fibres always exhibited high ATPase activity, whereas one of the nuclear bag fibres had low ATPase and the other either low or medium to high ATPase activity. However, the ATPase activity of de-efferented muscles was generally lower than that of normal muscles. It can be concluded that intrafusal fibres do acquire their fibre type characteristics after fusimotor denervation despite complete deprivation of nerve impulse activity during the postnatal period when intrafusal fibre types differentiate in normal spindles.
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    Structure, development and function of the protonephridia in trochophores of Pomatoceros triqueter (Annelida, Polychaeta, Sedentaria) (1974)
    Springer
    Cell & tissue research 156 (1974), S. 21-33 
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    ISSN: 1432-0878
    Keywords: Protonephridium ; Pomatoceros triqueter (Annelida, Polychaeta, Sedenta-ria) ; Terminal cell ; Channel cell ; Development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary During the development of the intermediate and late gastrula of Pomatoceros triqueter, the terminal and channel cells grow towards each other and form the protonephridium. They interdigitate through lateral microvilli. The junctions between the cells form filtration clefts, which are bridged by fibrils.
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    The postnatal development of the sexually dimorphic duct system and of amylase activity in the submandibular glands of mice (1975)
    Springer
    Cell & tissue research 157 (1975), S. 411-422 
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    ISSN: 1432-0878
    Keywords: Submandibular gland (mice) ; Sex-dimorphism ; Amylase ; Development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The submandibular glands of developing and mature Strong A mice were studied by light and electron microscopy. The glands of both sexes show the same cell types during development, but during maturation the glands display a degree of sex-dimorphism. Striated ducts, which differentiate from the larger intralobular ducts present in the neonatal gland, first appear by 5 days of age and reach their mature condition by 20 days of age. Granular convoluted tubule cells, which differentiate from striated duct cells, are first seen at 15 days of age in both sexes. Subsequently, they show a more rapid development in males than in females, and are dimorphically represented by 20 days of age. Intercalated ducts in the neonatal gland contain nongranular and granular cells. With maturation the number of granular cells decreases, apparently due to their conversion into the nongranular type, with their eventual disappearance from the glands of adult males. Their retention in adult females further defines the sexual dimorphism shown by these glands. Amylase activity in gland homogenates is first detectable at 20 days of age in both sexes. During development the male glands show a rapid rise in levels of amylase activity, whereas female glands show a more gradual rise. In mature animals, male glands have higher levels of amylase activity than female glands. The developmental and adult status of amylase activity parallels that of the granular convoluted tubules.
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    Subcommissural organ-associated neurons in fetal and neonatal rabbit (1975)
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    Cell & tissue research 159 (1975), S. 195-204 
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    ISSN: 1432-0878
    Keywords: Subcommissural organ ; Neurons ; Development ; Rabbit
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Neurons which initially lie in the basal region of the subcommissural organ (SCO) were investigated in 20 rabbit fetuses from day 15 to 30 of gestation, and in eight neonatal, 4 and 8 day old rabbits. These SCO-associated neurons, first observed on day 17 of gestation, develop into (1) a rostral mesodiencephalic nerve cell group situated in an area dorsal to the rostral-most part of the SCO and (2) a more caudal layer of single neurons extending throughout the length of the SCO. The present findings are discussed in relation to recent histochemical studies that demonstrated AChE-positive neurons in the pineal complex and subcommissural area of frogs and to recent fluorescence microscopic studies in fetal and adult rats in which a 5-HT system is known to extend from the nucleus raphe dorsalis (B7) along the SCO to the pineal stalk and habenular region. The term “SCO-associated neurons” is a purely morphological way of describing the neurons in question as the neural interconnections of these neurons are still a matter of speculation.
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    Ultrastructural studies on neuromuscular contacts and the formation of junctions in the flight muscle of Antheraea polyphemus (Lep.) (1975)
    Springer
    Cell & tissue research 159 (1975), S. 245-266 
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    ISSN: 1432-0878
    Keywords: Neuromuscular junctions ; Rete synapticum ; Development ; Antheraea ; (Lepidoptera) ; Trophic action ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructure of neuromuscular connections on developing dorsolongitudinal flight muscles was studied in the moth Antheraea polyphemus, Undifferentiated membrane contacts between axon terminals and muscle-fiber anlagen are present in the diapause pupa. They persist during the period of nerve outgrowth, which probably provides a pathway of contact guidance. By the 4th day of adult development some of these contact areas have differentiated into structures similar to neuromuscular junctions although differentiation of muscle structure does not start earlier than the eighth day. Dense-cored vesicles are abundant in many axon terminals at the beginning of development. They later decrease in number quite rapidly. The significance of the above-mentioned early junctions, their possible mode of action and the role of the dense-cored vesicles are discussed. It is proposed that they exercise a stimulating (trophic) influence on the growth of the undifferentiated muscular tissue. The imaginai neuromuscular junctions are formed during the second half of adult development. Clusters of vesicles and electron-dense depositions along the inner face of the axolemma seem to initiate junction formation. Glial processes then grow between axoand sarcolemma and divide the large contact area into several small segments. Mutual invaginations and protrusions of the sarcolemma and the glial cell membrane subsequently form an extensive “rete synapticum.” Six days before eclosion the glial and sarcoplasmic parts of the rete synapticum are similar in size. Up to eclosion, all glial processes shrink and increase in electron density. Most of the observations are discussed also in relation to findings in vertebrates.
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    Ultrastructural analysis of the granulosa — Luteal cell transition in the ovary of the dog (1975)
    Springer
    Cell & tissue research 160 (1975), S. 155-176 
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    ISSN: 1432-0878
    Keywords: Ovary, dog ; Corpus luteum ; Development ; High voltage electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The transition from ovarian granulosa to lutein cell during the estrus cycle of 60 pregnant and non-pregnant beagle bitches was analyzed by light and electron microscopy (both 100 and 1000 KV). Early proestrus was characterized by a gradual rise in serum estrogen levels, hyperplasia of the granulosa cells, the accumulation of follicular fluid, and the development of tortuous intercellular channels. During the second half of proestrus, serum estrogen levels continued to rise, but growth, division, and differentiation of the granulosa cells was minimal. Estrus was marked by the first acceptance of the male and a well-defined LH peak In the subsequent 24 hour period, the granulosa-lutein cells hypertrophy rapidly and develop a large Golgi apparatus, small profiles of granular endoplasmic reticulum, numerous microfilaments, and large gap junctions between the cells. Mitochondria also proliferate, enlarge, and elongate, but retain lamelliform cristae. Luteinization of the cells and progesterone secretion begin just after ovulation which in turn occurs about 24 hours after the LH peak. On the third and fourth day of estrus, numerous small vesicles of agranular endoplasmic reticulum fill the cytoplasm and the mitochondria swell up and round off. The vesicles rapidly fuse into whorled and flattened cisternae or anastomosing tubules of agranular endoplasmic reticulum, while the mitochondria develop tubulovesicular cristae. These structures gradually become organized with respect to the basal lamina. The Golgi apparatus is centered over the pole of the nucleus that faces the pericapillary space. Stacked and whorled cisternae of agranular ER develop in the lateral margins and avascular end of the cell while mitochondria and tubular elements of agranular ER predominate in the central medial and most basal portions of the cytoplasm. Microfilaments are ubiquitous and appear to be instrumental in this orientation process. The cell surface develops three distinct regional specializations that coincide with the underlying cellular compartment: interconnecting pleomorphic folds fill the pericapillary space; long tenous microvilli project from the lateral cell surface and form tortuous intercellular channels and canaliculi; and large gap junctions form along the margins of the cell furthest removed from the basal lamina. By the sixth day of estrus, the granulosa-luteal cell transition is nearly complete and serum progesterone levels are on the rise.
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    Intestinal enzymes activities in isolated villus and crypt cells during postnatal development of the rat (1977)
    Springer
    Cell & tissue research 176 (1977), S. 167-178 
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    ISSN: 1432-0878
    Keywords: Intestine (rat) ; Development ; Isolated cells ; Enzymes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary A modification of Weiser's (1973) cell isolation method was used in order to study the developmental pattern of various intestinal enzyme activities in villus and crypt cells of normal rats from 5 days after birth until 8 weeks. Alkaline phosphatase and enterokinase activities were always located in the upper villus zone during postnatal development. Enterokinase activity was higher in the upper villus cells during the third week of life than after this period. Aminopeptidase activity was located in the crypt cells during the first week, its maximum activity remained in this area until the third week. At this time, sucrase activity appeared in the crypt cells, then aminopeptidase and sucrase activities rose to the villus zone during the fourth week. Amylase activity was detected along the entire crypt-villus axis 5 days after birth, reaching maximum activity in crypt cells at the end of the first week and in the upper villus cells after the fourth week. In contrast with the other enzymes studied almost all amylase activity was soluble in the youngest animals whereas at weaning most of the activity appeared in a particulate form in the villus cells. But in the crypt cells the ratio between particulate and soluble form remained unchanged until the adult stage. Various hypotheses are advanced to explain the patterns of evolution of the different enzymes.
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    The postnatal development of myelinated nerve fibres in the visual cortex of the cat (1976)
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    Cell & tissue research 167 (1976), S. 265-288 
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    ISSN: 1432-0878
    Keywords: Myelinated fibres ; Visual cortex ; Stereology ; Development ; Electron microscopy ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary With the aid of stereological procedures the development of myelinated nerve fibres (MF) was quantitatively investigated in electron micrographs of the visual cortex from animals of different ages: 36 days-old, the age at which fibres first appear, through adulthood. A short description of tissue treatment, methods and qualitative results is given. The following quantitative results are presented: 1. Myelinization begins at about the 36th day postpartum and is not completed by the 164th day. At this time a lack of about 20% MF can be observed. 2. The average diameter of MF decreases from 1.3 μm to 0.8 μm from day 36 to adulthood. 3. The first MF appear near the border of the album. 4. Beginning with the 55th day, small MF arise in layer I, showing two periods of growth. 5. The maximum MF density in the region of layer IV corresponds to the strip of Baillarger. Other aspects of visual cortex development are dealt with in the Discussion. The following conclusions can be drawn: a) The growing of inand output-MF is completed first. b) The development of the internal connecting systems in layers I and IV begins a little later and is completed by the 5th month. c) The MF in layers II and III appear after the 4th month. Kaes (1907) has also described a continuation of MF growth in man lasting into the twenties.
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    Synaptic junction development in the spinal cord of an amphibian embryo: An electron microscope study (1973)
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    Cell & tissue research 137 (1973), S. 251-269 
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    ISSN: 1432-0878
    Keywords: Synapse ; Development ; Spinal cord ; Amphibian
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary An electron microscopical study has been made of the cervical spinal cord of Xenopus laevis embryos, from the time that the neural tube closes until the larvae were hatched and could swim. Sections of the whole cord were searched for intercellular junctions during this period. Two nonsynaptic types were found, the first were widely distributed puncta adherentia, the second were rare and similar to “gap” junctions. Membrane specializations with synaptic vesicles were first found when the neural folds had fused; “membrane-vesicle clusters” which looked like the presynaptic half of a synaptic junction were present, together with synaptic junctions lacking any postsynaptic membrane thickening or cytoplasm density. About four hours later, mature synaptic junctions with full thickening of the postsynaptic membrane, dense cytoplasm and striated or dense material in the synaptic cleft were present. Presynaptic mitochondria, dense-cored and flattened vesicles, fibre to fibre and fibre to cell body synapses were present from the first, as were synapses onto very fine dendrites which might be filopodia from dendritic growth cones. Synaptogenesis may start with the accumulation of vesicles in dense cytoplasm near a thickened cell membrane; the postsynaptic element becomes associated with this “membrane-vesicle cluster” and matures by increasing cleft and cytoplasmic density, and by membrane thickening.
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    Myelogenesis and estimation of the number of axons in the anterior commissure of the chick (Gallus gallus) (1985)
    Springer
    Cell & tissue research 239 (1985), S. 661-666 
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    ISSN: 1432-0878
    Keywords: Anterior commissure ; Development ; Morphometry ; Myelogenesis ; Aves ; Gallus gallus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary By use of light- and electron microscopy the anterior commissure of the chick was studied at different times during development. Between the 19th day of incubation and the 35th day after hatching the cross-sectional area of the anterior commissure, as determined from mid-sagittal sections, undergoes a 6-fold increase in size. Thereafter the area remains fairly constant. The total number of fibres in the anterior commissure was estimated to be 89000. The full complement of fibres is already present by the 19th day of incubation. Myelogenesis occurs mainly between the 19th day of incubation and the 35th day after hatching, concomitant with the increase in cross-sectional area. From the 35th day after hatching, myelinated fibres comprise approximately 40% of the total number of fibres. The median diameter of unmyelinated fibres is about 0.35–0.40 μm. The median diameters of myelinated axons and fibres are 0.8–1.0 μm and 1.1–1.3 μm, respectively.
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    Development of sensory innervation in chick skin: comparison of nerve fibre and chondroitin sulphate distributions in vivo and in vitro (1994)
    Springer
    Cell & tissue research 277 (1994), S. 519-529 
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    ISSN: 1432-0878
    Keywords: Key words: Skin ; Development ; ontogenetic ; Chondroitin sulphate proteoglycan ; Neuritic guidance ; Immunocytochemistry ; Chicken
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. In bird skin, nerve fibres develop in the dermis but do not enter the epidermis. In co-cultures of 7-day-old chick embryo dorsal root ganglia and epidermis, the neurites also avoid the epidermis. Previous studies have shown that chondroitin sulphate proteoglycans may be involved. Chondroitin sulphate has therefore been visualized by immunocytochemistry, using the monoclonal antibody CS-56, both in vivo and in vitro using light and electron microscopy. Its distribution was compared to those of 2 other chondroitin sulphate epitopes and to that of the growing nerve fibres. In cultures of epidermis from 7-day-old embryonic chicks, immunoreactivity is found uniformly around the epidermal cells while at 7.5 days the distribution in dermis is heterogeneous, and particularly marked in feather buds. In vivo, chondroitin sulphate immunoreactivity is detected in the epidermis, on the basal lamina, on the surfaces of fibroblasts and along collagen fibrils. This localization is complementary to the distribution of cutaneous nerves. Chondroitin sulphate in the basal lamina could prevent innervation of the epidermis and the dermal heterogeneities could partly explain the nerve fibres surrounding the base of the feathers. Chondroitin sulphate could therefore be important for neural guidance in developing chick skin.
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    The development of a hypothalamic monoaminergic system for the regulation of the pars intermedia activity in Xenopus laevis (1973)
    Springer
    Cell & tissue research 143 (1973), S. 229-238 
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    ISSN: 1432-0878
    Keywords: Hypothalamo-hypophysial system ; Development ; Monoamines ; Colour change ; Fluorescence microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In Xenopus laevis the development of hypothalamic monoaminergic cells was studied in relation to adaptation to background colour. The first melanophores appear at stage 33/34 (normal table of Nieuwkoop and Faber, 1956), gradually increasing in number. The melanine granules are dispersed throughout the cell, irrespective of the background colour. The dispersion apparently is caused by MSH released by the developing pars intermedia cells. Between stage 39 and stage 41, larvae placed on a white background changed colour from black to white due to aggregation of the melanine granules within the melanophores. With Falck's method for demonstrating monoamines, a small number of fluorescent cells was observed in the hypothalamus simultaneously with the first background-dependent colour change. These cells were arranged in a paired nucleus, bordering the third ventricle. Initially, the nucleus extends from 50 microns behind the optic chiasma to the lateral dilatations of the third ventricle; 8–10 hours later, similar cells were also found at the lateral dilatations and in the dorso-lateral part of the infundibular lobe. The cells have apical processes protruding in the ventricular lumen. Fluorescent axons, originating from the cells, were occasionally observed. Considering the above-mentioned results in combination with the electron microscopical data of Nyholm (1972), it is concluded that the MSH producing cells are under monoaminergic nervous control from the beginning of background colour adaptation.
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    Ultrastructure of the lamina propria in the ovine seminiferous tubule (1974)
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    Cell & tissue research 150 (1974), S. 481-492 
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    ISSN: 1432-0878
    Keywords: Seminiferous tubule, ovine ; Lamina propria ; Development ; Endocrine factors ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructure of the lamina propria in the ovine seminiferous tubule was studied from 54 days (postcoitum) fetuses up to sexual maturity. In young animals (aged about two months) the effect of hypophysectomy and/or hormones was also analyzed. Initially, large areas of the lamina propria already show signs of morphological differentiation. The non cellular component is a single or sometimes double lamella. Outwardly, the cellular component is represented by rounded connective tissue cells or by elongated cells, exhibiting 80 Å filaments in the cytoplasm and arranged in 3 to 4 layers. By the first week after birth, the non cellular component is formed by 8 to 10 lamellae and the cellular component shows typical contractile cells, the fibroblasts being now located only in the periphery. Basically, the same aspect is found in the adult ram, thus differing from the more extensively studied prototypes of lamina propria architecture of rodents or primates. In as much as the sheep lamina propria differentiates precociously, probably induced by fetal testicular hormones, it is relatively insensitive to hypophysectomy or hormonal substitution. Hypophysectomy and cyproterone acetate administration cause intracytoplasmic lipid deposition in the contractile cells, the other components being not changed. Some questions are raised concerning the role of this peculiar lamina propria in the function of the blood-testis barrier.
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    Development of secondary lamellae of the gills of the trout, Salmo gairdneri (Richardson) (1974)
    Springer
    Cell & tissue research 151 (1974), S. 509-523 
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    ISSN: 1432-0878
    Keywords: Gill ; Trout ; Secondary lamellae ; Development ; Light and electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary A light and electron microscope study of secondary lamellae of trout developing at 10° C is described. Collagen is secreted by mesenchyme cells in the connective tissue of the developing gill filament. This becomes enclosed in infoldings around the peripheries of mesenchyme cells. These cells become aligned in a single plane within folds of basement membrane and epithelium. The basement membrane of opposite sides of the fold becomes connected by a thick layer of collagen. Blood spaces form around the margin of the fold, connecting afferent and efferent filament blood vessels. Endothelial granules form in cells lining the outer border of the marginal channel when blood flow begins. Rows of pillar cells separate from the proximal layer of mesenchyme cells as the secondary lamellae develops further. New secondary lamellae are added at the filament tips. At 28 days, the basement membrane consists of 2 layers, a fine fibrous layer and 5–15 orthogonally arranged layers of collagen fibres. By 31 days, the collagen is arranged at random and the layer is thinner. A clear layer is also present by 67 days. A multilayered epithelium containing mucous and chloride cells is present at 28 days. By 102 days, the secondary lamellae are covered by 2 layers of epithelial cells only. Chloride cells are present in much greater numbers in developing gills than in the adult.
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    The ultrastructure of the human fetal pineal gland (1974)
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    Cell & tissue research 152 (1974), S. 13-30 
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    ISSN: 1432-0878
    Keywords: Human fetal pineal gland ; Development ; Secretion ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructure of the pineal gland of 18 human fetuses (crown-rump lengths 30–178 mm) was investigated. The pineal gland exhibits a pyramidal shape and consists of an anterior and posterior lobe. Only one parenchymal cell type, the pinealocyte, was observed. Few neuroblasts were seen between the pinealocytes and in the extended perivascular space. The pinealocytes possess all the organelles necessary for hormone synthesis. No specific secretory granule could be observed. The organ is abundantly vascularized and richly innervated. The morphology of the capillaries indicates the existence of a blood-brain barrier. The ultrastructure of the human fetal pineal gland suggests that the gland has a secretory function in early intrauterine life.
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    Zur Funktion der Mikrotubuli beim Wachstum der Myofibrillen von Insektenflugmuskeln (1970)
    Springer
    Cell & tissue research 109 (1970), S. 138-146 
    Details
    ISSN: 1432-0878
    Keywords: Insect muscles ; Development ; Microtubuli ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung In der indirekten Flugmuskulatur von Phormia terrae-novae kann die Entwicklung der Myofibrillen deutlich in eine Anlage- und eine Wachstums-Phase unterteilt werden. Zu Beginn der Wachstumsphase wurde Puppen eine Lösung von Colchicin in die rechte Metathoraxhälfte injiziert. Als Folge dieser Behandlung lösten sich zunächst die Mikrotubuli in der Flugmuskulatur auf. In späteren Entwicklungsstadien bildeten sich atypische Verzweigungen der Myofibrillen, die zu einer partiellen Desorientierung der kontraktilen Strukturen führten. Ein Mechanismus, der solche Störungen des Orientierungmusters in der Normalentwicklung möglicherweise verhindert, wird diskutiert.
    Notes: Summary In the blowfly Phormia terrae-novae the development of myofibrils of indirect flight muscles can be divided into periods of predisposition (anlage) and of growth. At the beginning of the growth period microtubules are disrupted by injection of colchicine. This disruption is followed by the formation of atypical ramifications of myofibrils at Z-discs leading to numerous disoriented myofibrils in late developmental stages. A possible mechanism preventing these alterations during normal development is discussed.
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    Mode de formation des inclusions lamellaires dans le poumon embryonnaire de poulet (1970)
    Springer
    Cell & tissue research 110 (1970), S. 72-84 
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    ISSN: 1432-0878
    Keywords: Lung cells ; Chick embryo ; Lamellar inclusions ; Ultrastructure ; Development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Résumé Les pneumocytes granuleux, qui constituent l'un des principaux types cellulaires de l'épithélium pulmonaire, sont caractérisés par la présence de volumineuses inclusions osmiophiles lamellaires. Nous avons étudié l'apparition et l'origine de ces inclusions dans l'épithélium du poumon embryonnaire de Poulet, en l'examinant à différents stades du développement. Les premières inclusions lamellaires apparaissent dans le poumon de l'embryon de 16 jours. A ce stade, quelques lamelles concentriques entourent une zône centrale amorphe étendue; la périphérie des inclusions contient toujours de petites structures granulaires. Les jours suivants le nombre de cellules contenant des inclusions lamellaires augmente rapidement; en même temps, les lamelles deviennent plus nombreuses. A 19 jours, les inclusions lamellaires ont un aspect semblable à celui qu'elles ont dans les poumons d'animaux adultes. Dès l'apparition des ébauches pulmonaires, à 2 1/2 jours d'incubation, les cellules épithéliales contiennent des inclusions typiques: les inclusions granulaires. Ces organites sont caractérisés par un centre granulaire, qu'entouré un système membranaire. Ce système, simple chez le jeune embryon, évolue ensuite en se compliquant; chez l'embryon de 16 jours, il s'enroule en plusieurs couches autour de la masse centrale. Au moment où les premières inclusions lamellaires apparaissent, le nombre des inclusions granulaires augmente rapidement; on les trouve souvent étroitement associées à des vacuoles lipidiques. L'analyse des relations entre inclusions lamellaires, inclusions granulaires et vacuoles lipidiques suggère que l'inclusion lamellaire résulte de la collaboration entre une vacuole lipidique et plusieurs inclusions granulaires.
    Notes: Summary The granular pneumocytes, one of the main cellular types of the lung epithelium, are characterized by the presence of large osmiophilic lamellar inclusions. The appearance and origin of these inclusions has been studied in the epithelium of chick embryonic lung at different developmental stages. Lamellar inclusions are first seen in the lung of 16 day old embryos. At this stage, few concentric lamellae surround a large amorphous center; the periphery of the inclusions always contains small granular structures. In the following days, the number of cells containing these lamellar inclusions increases rapidly, while their lamellae progressively become more numerous. In 19 day old embryos, the lamellar inclusions are similar to those in the lungs of adult animals. From the earliest formation of the bronchial primordia, their epithelial cells contain a number of typical “granular” inclusions. These organelles are characterized by a granular center, enclosed in a membranous system. This structure becomes more complex as the embryo develops; in the 16 day old embryo, the multilayered membranous system coils around the granular center. At the time when lamellar inclusions first appear, granular inclusions increase rapidly in number and are often found in close association with lipidic vacuoles. The relationships between lamellar inclusions, granular inclusions and lipidic vacuoles are discussed. The evidence suggests that a lamellar inclusion arises from the cooperation of several granular inclusions and a lipidic vacuole.
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    Fine structure of the pterin layer in the dermis of Rana pipiens (1971)
    Springer
    Cell & tissue research 113 (1971), S. 558-563 
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    ISSN: 1432-0878
    Keywords: Pterin layer ; Pigmentation ; Dermis ; Development ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The fine structure of the pterin layer was investigated in both wild type Rana pipiens and Rana pipiens homozygous for the speckle mutant gene. No difference in morphology of the layer was noted between the wild type and mutant. The layer lines the outer surface of the stratum compactum of the dermis and separates this stratum from the stratum spongiosum. The pterin layer consists of extra-cellular material and contains membrane-bounded granules filled with fine spicules. Many of the spicules are somewhat similar in appearance to the initial calcification loci present in developing membrane bone. The layer first appears in the tadpole at approximately stage 14 (Taylor and Kollros, 1946); subsequent developmental stages are described.
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    Ultrastructural observations on the postnatal development of the rat prostate (1971)
    Springer
    Cell & tissue research 113 (1971), S. 157-173 
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    ISSN: 1432-0878
    Keywords: Prostate ; Development ; Ultrastructure ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The postnatal development of the rat prostate has been studied with the electron microscope. Major developmental changes begin during the second week after birth and involve organelles associated with the formation of secretions. The amount of granular endoplasmic reticulum and the size of the Golgi complex increase greatly. Large vacuoles that probably contain secretory material are formed, and the lumen of the prostatic acini appears to contain secreted material. Large lysosomes with polymorphic interiors are present as early as 10 days after birth, and they become numerous by the end of the third week. Differences in fine structure between the different lobes of the prostate are detectable in 10–14 day old rats. The subsequent differentiation of the granular endoplasmic reticulum into the forms characteristic of the different prostatic lobes is described. The initial changes in the prostate occur in advance of sexual maturity of the animal, and the adult appearance of the gland is attained by 4–5 weeks after birth.
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    URL: http://dx.doi.org/10.1007/BF00339413
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    Über die Mikrovillibildung im fetalen Rattendünndarm (1971)
    Springer
    Cell & tissue research 114 (1971), S. 546-556 
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    ISSN: 1432-0878
    Keywords: Microvilli ; Small intestine ; Brush border ; Development ; Golgi apparatus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Die Frage, auf welche Weise die Enterocyten des fetalen Rattendünndarms das für die Mikrovillibildung benötigte Membranmaterial liefern, wurde elektronenmikroskopisch untersucht. Es wird angenommen, daß hufeisenförmige Strukturen, die aus mit elektronendichtem Material bedeckten Elementarmembranen bestehen und möglicherweise Längsschnitten durch kappenförmige Gebilde entsprechen, in das apicale Plasmalemm eingebaut werden und für die Bildung der Mikrovillispitzen verantwortlich sind. Diese Annahme gründet sich in erster Linie auf die Feststellung eines nahezu identischen Durchmessers von „Hufeisen“ und Mikrovilli, auf die Lokalisation der „Hufeisen“ im Terminalgespinst und ihr zahlenmäßiges Verhalten während der Mikrovillibildung. Die „Hufeisen“ entstehen im Golgi-Apparat.
    Notes: Summary The origin of membranes required for the formation of microvilli has been investigated electronmicroscopically in enterocytes of fetal rat small intestine. It is assumed that horseshoe-like structures consisting of unit membranes covered with electron-dense material, which probably represent longitudinal sections through cap-like structures, are incorporated into the apical cell membrane and give rise to the tips of microvilli. This assumption is based chiefly on the almost identical diameters of “horseshoes” and microvilli, the localization of “horseshoes” in the terminal web, and the time of appearance and disappearance of “horseshoes” with regard to development of microvilli. There are indications that the “horseshoes” originate in the Golgi apparatus.
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    Development of the innervation in the human pineal organ (1971)
    Springer
    Cell & tissue research 115 (1971), S. 396-415 
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    ISSN: 1432-0878
    Keywords: Human pineal organ ; Development ; Innervation ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary This investigation is concerned with pineal organs of human embryos 60 to 150 days old. At every stage central nerve fibres enter the pineal organ by way of the habenular commissure, but are restricted to the pineal's proximal part. On about the 60th day of the development the sympathetic nervus conarii grows into the distal pole of the pineal organ from a dorso-caudal direction and plays the predominant part in the innervation of the pineal organ. After penetrating, it soon branches out and forms a network in the pineal tissue. Much later, not until the 5th embryonic month, sympathetic nerves appear accompanying the supplying vessels in the perivascular spaces. After a short time these nerves pierce the outer limiting basement membrane and penetrate the parenchyma. Towards the end of the 5th embryonic month the axons of the sympathetic nerves form varicosities containing clear and dense core vesicles. At this point large amounts of laminated granules appear primarily in cell processes, probably of pinealocytes. Isolated granules also occur in the varicosities of axons. The granules encountered here are most likely secretory granules.
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    Development of the ocular adrenergic nerve supply in man and guinea-pig (1971)
    Springer
    Cell & tissue research 118 (1971), S. 579-592 
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    ISSN: 1432-0878
    Keywords: Bye ; Innervation ; Adrenergic ; Development ; Manuals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The development of adrenergic nerves to the anterior eye segment was studied in human and guinea-pig embryos. Adrenergic terminals had already appeared in the earliest human embryos available (4–6 cm). They first appeared mainly in nerve trunks in the primitive chorioid, especially in the region of the developing ciliary body. Adrenergic nerves then grow into different structures of the eye as these develop, but typical terminals in contact with effector cells appeared late during the development, about the 25–30 cm stage. No adrenergic nerves were observed in the chamber angle. Corneal adrenergic nerves (also intraepithelial terminals) appeared much more frequently in embryos than in adults. No adrenergic neurons were observed in the retina. In the guinea-pig, the first adrenergic fibres were observed at about gestation day 35. The general principle of the development was very similar to that of the humans. At gestation day 45 to 50, the supply of adrenergic fibres was essentially that of the adult animal, except that the corneal adrenergic fibres were increasing until just before birth and that the adrenergic terminals of the chamber angle appeared shortly before term.
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    Ultrastructural features of the developing hypothalamo-hypophysial axis in the rat (1971)
    Springer
    Cell & tissue research 119 (1971), S. 208-226 
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    ISSN: 1432-0878
    Keywords: Median eminence ; Hypophysial portal vessels ; Pars distalis ; Ultrastructure ; Development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Nerve fibres containing granular vesicles first appear in the median eminence of the rat on the 16th foetal day while secretory granules in the cells of the adenohypophysis are not present till the 17th foetal day. These observations suggest that the differentiation and early activity of pars distalis cells may depend on substances elaborated at nerve terminals in the median eminence. Although the loops of the primary plexus of portal vessels do not develop until the 4th postnatal day, substances released by nerve fibres in the neurohypophysis could reach the pars distalis through vessels already present at the 15th foetal day in the mesenchyme between the diencephalon and the adenohypophysis. This view is supported by the fact that the earliest cells to exhibit ultrastructural evidence of secretory activity are in the rostral pole of the pars distalis, the first region of the gland to become vascularized. The earliest granules to appear in the cells of the pars distalis correspond to those which are considered to contain mucoprotein hormones; somatotrophin type granules were seen only in postnatal tissues. The finding that, in the median eminence, the development of granular vesicles precedes that of agranular vesicles is discussed with reference to the times at which neurosecretory materials and monoamines become detectable in the region.
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    Ultrastructure of sympathetic ganglion cells and granule-containing cells in the paracervical (Frankenhäuser) ganglion of the newborn rat (1972)
    Springer
    Cell & tissue research 126 (1972), S. 25-40 
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    ISSN: 1432-0878
    Keywords: SIF-cells ; Short adrenergic neurons ; Biogenic amines ; Osmiophilic granules ; Innervation of uterus ; Development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary A study was made of the ultrastructure of the paracervical (Frankenhäuser) ganglion of the newborn rat, using immersion fixation by glutaraldehyde (2.5%) followed by OsO4 (1%), or KMnO4 (3%) fixation. The cells containing dense—core vesicles were divided into three groups: (1) primitive sympathetic cells, (2) cells containing some dense-core vesicles 700–1100 Å in size and structurally resembling sympathetic neurons, called principal neurons, and (3) cells containing many dense-core vesicles with a larger, darker dense core, 800–2000 Å in diameter, called granule-containing cells. Using glutaraldehyde-osmium fixation, the principal neurons were further divided into dark and light cells on the basis of electron opacity of the cytoplasmic matrix. The granule-containing cells were believed to correspond to the small, intensely fluorescent cells (SIF-cells) previously described using the formaldehyde-induced fluorescence technique. On the basis of the amount of granules, the granulecontaining cells were classified as mature or maturing SIF-cells and as more primitive SIF-cells, and developing sympathicoblasts. The development of synapses in autonomic ganglia was discussed.
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    Ultrastructure of the developing thymus of the leopard frog (Rana pipiens) (1972)
    Springer
    Cell & tissue research 127 (1972), S. 323-346 
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    ISSN: 1432-0878
    Keywords: Thymus ; Frog ; Development ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary A study of the ultrastructure of the developing thymus of the leopard frog (Rana pipiens) revealed that the thymus had undergone all of the major changes which would persist through larval life and metamorphosis by the time that the animals had reached larval stage IV of Taylor and Kollros (1946). These changes included development of an outer, lymphoid cortical region and an inner, essentially nonlymphoid medulla; mitotic activity among lymphoid cell precursors and the formation of the first small lymphocytes; development of complex cysts containing PAS-positive material and the appearance of other signs of secretory activity among epithelial cells of the medulla; and differentiation of large myoid cells containing bundles of striated muscle fibrils. The changes are particularly noteworthy because they first appear during a period in which the animals are known to be developing the capacity to respond immunologically to allografts.
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    The development of glio-vascular relationships in the rat spinal cord (1972)
    Springer
    Cell & tissue research 128 (1972), S. 555-563 
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    ISSN: 1432-0878
    Keywords: Astrocytes ; Capillaries ; Spinal cord ; Blood brain barrrier ; Development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Glio-vascular relationships were studied in the developing rat cervical spinal cord with electron microscopy. Capillaries were first evident on the eleventh prenatal day and were surrounded by undifferentiated cells and neuroblasts separated from the capillary wall by a perivascular space. This space persisted until day thirteen, when basement membranes began to appear. Small cellular processes containing glycogen were visible adjacent to the capillary basement membrane beginning at day fifteen and became more prominent as development proceeded. The origin of these cellular processes was not apparent, but they were most likely collaterals of epithelial elements. In prenatal animals neuroblasts or neurons were in direct contact with the capillary basement membrane. Cells resembling adult astrocytes were first observed during the nineteenth day. Astrocytic processes completely invested the capillaries, separating them from neurons in the spinal cord of all postnatal animals.
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    Ultrastructural changes in developing midgut epithelium of Calliphora erythrocephala meigen (1972)
    Springer
    Cell & tissue research 129 (1972), S. 278-289 
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    ISSN: 1432-0878
    Keywords: Midgut epithelium ; Insects ; Development ; Metamorphosis ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructural alterations in the anterior midgut epithelium of the fly Calliphora were investigated by electron microscopy. Nine developmental stages, from late larval to late adult, were studied. During metamorphosis, a tube is formed by proliferation of undifferentiated cells residing in cell nests in the basal part of the larval epithelium. The process of microvillus formation is described and compared with that in the embryonic stage. Differences between larval and imaginal cells were found in the rate of microvillus formation and in the occurrence of dense vesicles. The formation of a basal labyrinth coincides roughly with microvillus formation. Glycogen deposits occur mainly in the pupal stage and are almost always absent after emergence. Epithelial crypts are formed in late pupae by modification of the existing layer of cells together with a localized development of muscle fibres. In the adult stage changes may take place in the form of the cell apex, which generally assumes a more pointed shape, and in the amount of osmiophilic material, aggregating almost exclusively in the supranuclear part of the cell.
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    Development of the olfactory organ in the rainbow fish Nematocentris maccullochi (Atheriniformes, Melanotaeniidae) (1979)
    Springer
    Cell & tissue research 200 (1979), S. 53-68 
    Details
    ISSN: 1432-0878
    Keywords: Olfactory organ ; Development ; Melanotaeniidae ; Scanning and transmission electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The development of the olfactory organ in the rainbow fish, Nematocentris maccullochi, was studied using scanning and transmission electron microscopy; it was compared with the developmental process in other teleosts, especially in the closely related atherinids and cyprinodonts. The formation of the nares parallels that in atherinids, salmonids, cyprinids and heterosomats, but differs from that found in cyprinodonts. Another ontogenetic feature in which the olfactory organs of the rainbow fish and also of atherinids differ from those of cyprinodonts, is the occurrence of transitory kinociliary cells which disappear during the postlarval period. The divergent evolutionary pathways are discussed with reference to experimental investigations. During development, ciliated and microvillous receptor cell types occur. At the primary larval stage ciliated receptor neurons are exclusively present. At a later stage the microvillous type develops and becomes equal in frequency. Thus, the microvillous receptor represents a separate type of olfactory neuron and is not a progenitor of the ciliated receptor cell.
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    Muscle development during vertebrate limb outgrowth (1999)
    Springer
    Cell & tissue research 296 (1999), S. 131-139 
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    ISSN: 1432-0878
    Keywords: Key words Limb ; Development ; Myogenesis ; Vertebrate ; Transcription factors ; Somites
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Limb development has become one of the model systems for studying vertebrate development. One crucial aspect in limb development is the origin, differentiation and patterning of muscle. Much progress has been made in recent years towards understanding this process. One of the general observations is that the genes involved in limb muscle development appear to be very similar to those involved in muscle development in other regions of the embryo. In this review, we summarize some of the genes and mechanisms that regulate limb muscle development and discuss various avenues along which a deeper understanding can be gained of how muscle cells originate and differentiate in different tissues during vertebrate development.
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    Détection par immunofluorescence des cellules corticotropes et mélanotropes dans l'hypophyse de la grenouille, Rana temporaria L., au cours du développément (1973)
    Springer
    Cell & tissue research 142 (1973), S. 571-580 
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    ISSN: 1432-0878
    Keywords: Hypophysis ; Rana temporaria ; Development ; Corticotropin cells, melanotropin cells ; Immunofluorescence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary During the embryonic and larval developmental stages of the frog, Rana temporaria L, anti-β 1–24, α 17–39 corticotropine, α and β MSH antibodies were used to define, with immunofluorescence technique, the appearence of corticotropic and melanotropic cells. A very small number of fluorescent corticotropic cells appears for the first time during the embryonic stage (10 mm), just before the differentiation of the pars intermedia. The cells are small, their large nucleus is surrounded by a fine rim of fluorescent cytoplasm. During premetamorphic stage, the anti-ACTH antibodies (anti-β 1–24 and anti-α 17–39 corticotropine) reveal more fluorescent cells in the whole pars distalis. The pars intermedia cells can also be visualized by both antisera. At the end of prometamorphosis and during climax the corticotropic cells show a more precise localization. As in adult frog pars distalis, they are concentrated in the rostral half of the lobe. With the same technique anti-α and β MSH antibodies reveal only the cells of the pars intermedia. No other cell type of the pars distalis reacts with these antibodies. This technique has the advantage to show that the ACTH and the MSH cells appear very early during the embryonic life.
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    Effect of hydrocortisone on the extra-adrenal intensely fluorescent chromaffin and non-chromaffin cells in stretch preparations of the newborn rat (1973)
    Springer
    Cell & tissue research 146 (1973), S. 565-578 
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    ISSN: 1432-0878
    Keywords: Sympathetic neurons ; Chromaffin cells ; SIP cells (Newborn rat) ; Development ; Administration of hydrocortisone ; Stretch preparations ; Fluorescence microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Air-dried stretch preparations were used to study adrenergic nerve fibres and catecholamine-containing cells with the formaldehyde-induced fluorescence method in the abdominal tissue block containing the para-aortic paraganglia, in the neurovascular structures of the cervical region including the carotid body, in the bladder, in the ileum, in the mesentery, in the vagus nerve and in the sympathetic ganglia of 5- or 15-day-old rats. The adrenergic nerves and the catecholamine-containing cells were well preserved and showed little or no diffusion of amines. While most intensely fluorescent cells of the main para-aortic body disappeared during the first two postnatal weeks, some such cells survived and they showed long, slender fluorescent processes. Administration of 20 mg/kg of hydrocortisone acetate daily for 5 days after birth caused a striking increase in the number and size of the clusters of the intensely fluorescent cells in the organ of Zuckerkandl, in the sympathetic ganglia and in the bladder, as well as an increase in the fluorescence intensity of the carotid body. In rats treated with hydrocortisone for 5 days and left to recover for 10 days an increased fluorescence was still observed. However, in the organ of Zuckerkandl the intensely fluorescent cells of hydrocortisone-treated 15-day-old rats showed less processes than those of the control rats of the same age.
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    Ultrastructural study on the hypothalamic-hypophysial-adrenal axis in fetal rats (1976)
    Springer
    Cell & tissue research 168 (1976), S. 549-559 
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    ISSN: 1432-0878
    Keywords: Hypothalamic-hypophysial-adrenal axis ; Rat ; Development ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The adrenal glands of decapitated and encephalectomized fetal rats were investigated electron microscopically and compared to those of normal intact fetal rats. Although the adrenal cortices did not show three zones (zona glomerulosa, fasciculata, and reticularis) on the 16.5th day of gestation when the decapitation or encephalectomy was carried out in utero, the zonation was recognized in fetuses operated on the 21.5th day of gestation. The same was true for normal control fetuses. However, cytoplasmic characteristics suggesting steroidogenesis in the cortical cells were reduced to various degrees in the encephalectomized or decapitated fetuses, especially in the latter ones. The change in cytoplasmic appearance was more conspicuous in the inner portion of the cortex. This result suggests that for the maintenance of normal adrenocortical function the hypothalamus may be indispensable even during the prenatal life of rats.
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    URL: http://dx.doi.org/10.1007/BF00216002
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    Development of secretory units of mouse submandibular gland (1970)
    Springer
    Cell & tissue research 110 (1970), S. 173-184 
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    ISSN: 1432-0878
    Keywords: Submandibular gland ; Secretory units ; Development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The fine structure of the secretory units of the mouse submandibular gland was studied according to the developmental sequence. The embryonic submandibular gland consists of terminal tubules and ducts. Myoepithelium is associated only with the terminal tubules, and the cells of the primary intercalated ducts show characteristics of the young striated duct cells. The major changes shortly after birth consist of: 1) opening of the secretory lumina, 2) increasing rough ER and its altered configuration, 3) dilatation of Golgi cisternae and 4) changes in the granular structure. These findings suggest that the salivary secretion first occurs after birth, and acinar differentiation or transformation of the secretory cells of the terminal tubules is induced and profoundly affected by the commencement of the secretory activity. In the intercalated ducts this process is somehow inhibited, and the granular cells found in the adult can be considered as the remnants of the secretory cells of the terminal tubules.
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    Struktur und Entwicklung des Integuments und der Oenocyten von Culex pipiens L. (Dipt.) (1970)
    Springer
    Cell & tissue research 110 (1970), S. 401-443 
    Details
    ISSN: 1432-0878
    Keywords: Integument ; Oenocytes ; Structure ; Development ; Culex pipiens
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung 1. Struktur und Entwicklung des Integuments und der larvalen Oenocyten während des Puppen- und pharaten Imaginalstadiums von Culex pipiens L. (Dipt.) werden beschrieben. 2. Auf- und Abbau der pupalen und die Anlage der imaginalen Cuticula verlaufen innerhalb enger zeitlicher Grenzen. 3. Beim Abbau der pupalen Endocuticula erscheint immer die Lamina der jeweils innersten Lamelle als „Häutungsmembran“. 4. Die Oenocyten sind durch ihr agranuläres, tubuläres endoplasmatisches Retikulum (ATER) und dessen Veränderungen charakterisiert. Die Struktur der Oenocyten gleicht der steroidproduzierender Wirbeltierzellen. 5. Das Aussehen der Oenocyten ändert sich kurz nach der Puppenhäutung hauptsächlich durch die kontinuierliche Zunahme von sog. Lipidvesikeln. Diese Vesikel entstehen durch Erweiterungen tubulärer Elemente des agranulären endoplasmatischen Retikulums. 6. Im Lichtmikroskop erscheinen diese Veränderungen als Kanalstrukturen („Sekretionsphase“) kurz nach der Puppenhäutung; später nimmt das Cytoplasma eine mehr vakuoläre Struktur an („Degenerationsphase“). 7. Mit Sudanschwarz B und Sudan III/IV lassen sich Lipide in den Erweiterungen der Tubuli des agranulären endoplasmatischen Retikulums (= Lipidvesikel) nachweisen. Nach Osmiumsäure-Fixierung sind sie nicht darstellbar. 8. Kurz vor der Imaginalhäutung kommt es in den Oenocyten zu massiver Autophagie. Dieser folgt ein Abbau des ATER und anderer Teile des Cytoplasmas. 9. Es gibt keinen Hinweis, daß die Oenocyten direkt für die Bildung der epicuticularen Lipide verantwortlich sind.
    Notes: Summary 1. Structure and development of the integument and the larval oenocytes during the pupal and pharate imaginai stage of Culex pipiens L. (Dipt.) are described. 2. Formation and digestion of the pupal cuticle and the formation of the imaginai cuticle take place within temporarily fixed limits. 3. While the pupal endocuticle is digested the lamina of the at times innermost lamella appears as a “ecdysial membrane”. 4. The oenocytes are characterized by their agranular, tubular endoplasmic reticulum (ATER) and its changes. The structure of the oenocytes is comparable to that of vertebrate cells engaged in steroid hormone synthesis. 5. The morphology of the oenocytes shortly after pupal ecdysis changes mainly by the continual raising of so called lipid vesicles. These vesicles arise from dilatations of tubular elements of the agranular endoplasmic reticulum. 6. Studied under the light microscope these changes appear as channel structures (“secretory phase”) shortly after pupal ecdysis; later on the cytoplasma becomes vacuolar in structure (“degeneration phase”). 7. By staining with Sudan black B and Sudan III/IV lipids can be demonstrated in dilatations of the tubules of the agranular endoplasmic reticulum. However they do not stain after fixation with osmium tetroxide. 8. In the oenocytes massive autophagy takes place just before imaginai ecdysis. It is followed by breakdown of the ATER and other parts of the cytoplasma. 9. There is no evidence that the oenocytes are directly responsible for the formation of epicuticular lipids.
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    The relationship between synaptic vesicles, Golgi apparatus, and smooth endoplasmic reticulum: a developmental study using the zinc iodide-osmium technique (1971)
    Springer
    Cell & tissue research 120 (1971), S. 332-345 
    Details
    ISSN: 1432-0878
    Keywords: Synaptic vesicles ; Development ; Golgi apparatus ; Smooth endoplasmic reticulum ; Zinc iodide-osmium technique
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Routine electron microscopy and a zinc iodide-osmium tetroxide technique (ZIO), recently found to be specific for synaptic vesicles, were used to study the origin of synaptic vesicles during postnatal development in the lumbosacral enlargement of the albino rat. In immature nervous tissue, a large number of vesicles, indistinguishable from synaptic vesicles (S vesicles), were found in the Golgi apparatus and in different portions of the axon where they were often intermingled with elements of the smooth endoplasmic reticulum (SER). Ten to twenty percent of these S vesicles within the Golgi apparatus as well as the majority of these vesicles in all parts of the axon were positive to ZIO. Much of the SER in axons was also positive. The number of vesicles and elements of the SER showed some decrease in the non-terminal portion of axons on day 21 and even more of a decrease in adult neurons. These data suggest that synaptic vesicles are produced in the Golgi apparatus and SER in immature neurons. The decrease in S vesicles and SER in adult neurons suggests a drop in synaptic vesicle production after synaptogenesis has ended. In addition, the material that has been studied shows that ZIO staining is not limited to synaptic vesicles during development since oligodendroglia and endothelial cells are also stained during this period.
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    Studies on the cytophysiology of the fat body of the American silkmoth (1972)
    Springer
    Cell & tissue research 124 (1972), S. 433-444 
    Details
    ISSN: 1432-0878
    Keywords: Insect ; Fat body ; Development ; Protein body ; Electron microscopy ; Histochemistry ; Lipoprotein ; Cytology ; Lipid globule ; Silkworm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary A developmental study at the electron microscopic level was conducted of the fat body cells of Hyalophora cecropia (L.). During the last larval instar the fat body increases in volume and the cells exhibit a well developed rough endoplasmic reticulum and protein bodies of diverse sizes. In the pupal fat body, the protein bodies appear to be enclosed by a double membrane and contain glycogen granules, ribosomes and mitochondrion-like structures. In addition, there are large lipid globules, cytolysomes and rough endoplasmic reticulum. The ultrastructure of the protein bodies suggests the development of large bodies by fusion of smaller protein bodies. Changes in fat body cell ultrastructure were followed during adult development and cytological evidence was obtained for the depletion of protein, glycogen and lipid in the female during this period. The female adult fat body cell contains free ribosomes, protein bodies, many mitochondria, a few lipid globules and glycogen granules. The male moth fat body cells have many mitochondria, a few glycogen granules, essentially no protein bodies, but an abundance of large lipid globules. Studies on the influence of egg maturation on the morphology of the fat body of Hyalophora gloveri (L.) revealed that ovariectomy of pupae yielded adults having more fat body than normal females, and that the fat body cells of the ovariectomized animals contained more glycogen, lipid and protein. Male pupae receiving ovarian implants developed into adults containing eggs and possessed more fat body than normal females but less than normal males. Very few glycogen granules were found in the fat body cells of normal males or males with implanted ovaries.
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    URL: http://dx.doi.org/10.1007/BF00335249
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    Die Ontogenie der basiconischen Riechsensillen auf der Antenne von Necrophorus (Coleoptera) (1972)
    Springer
    Cell & tissue research 129 (1972), S. 217-236 
    Details
    ISSN: 1432-0878
    Keywords: Olfactory sensilla ; Insects ; Development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung 1. 1. Der cuticuläre Apparat der basiconischen Sensillen von Necrophorus wird von 4 Zellen gebildet. Hüllzelle 1 bildet die Dendritenscheide, die trichogene Zelle den von Poren durchsetzten Teil des Haares, die tormogene Zelle die porenfreie Haarbasis und Hüllzelle 4 Sockel und Ringwall des Sensillums. 2. 2. Die Entwicklung der Haaranlage wird durch einen Wachstumsschub des von einer Scheide umgebenen Dendriten eingeleitet. Dieser Wachstumsschub ist der Längenzunahme des Dendriten während der Häutung bei Hemimetabolen homolog. 3. 3. Die trichogene Zelle umschließt den Dendriten nur bis zu 2 μ oberhalb der Epitheloberfläche und wächst dann neben ihm zur vollen Länge des künftigen Haares aus. Mit Abscheidung der Cuticulinschicht degeneriert das freie Ende von Dendrit und Scheide. 4. 4. Die Anlage des Poren-Tubulus-Systems beginnt mit der Abscheidung der Cuticulinschicht. Bei Erreichen von ca. 30% der Haarwandstärke sind auch die Porentubuli ausgebildet. Der äußere Liquorraum entsteht durch Zurückweichen der trichogenen Zelle aus dem neu gebildeten Haar. Der Dendrit wächst innerhalb der sich zurückziehenden trichogenen Zelle in das Haar ein. Wenige Stunden nach dem Schlüpfen beginnt sich der Dendrit durch Vesikulierung und anschließende Vesikelfusion in ca. 50 Äste aufzuspalten.
    Notes: Summary 1. 1. The cuticular apparatus of the basiconic sensilla in Necrophorus is built up by four cells: the enveloping cell No. 1 secretes the dendritic sheath, the trichogen cell produces the part of the hair with pores, the tormogen cell the hairbase without pores, and the enveloping cell No. 4 produces the base and the ringwall of the sensillum. 2. 2. The development of the hair starts with the growth of the sheathed dendrite. This growth is homologue to the increase in length of the dendrite during moulting in hemimetabole insects. 3. 3. The trichogen cell surrounds the dendrite only up to 2 μ distal of the epithelial surface and then grows beside the dendrite to the full length of the future hair. After having secreted the cuticulin layer the free ends of sheath and dendrite degenerate. 4. 4. The development of the pore tubules system begins with the secretion of the cuticulin layer. When the hairwall has reached 30% of its thickness the pore tubules are fully developed. The outer liquor space is formed by withdrawal of the trichogen cell from the newly built hair. The dendrite grows into the hair inside the retreating trichogen cell. Few hours after emerging from the pupa the dendrite begins to split into about 50 branches: between the microtubules of the dendrite many vesicles arise which then fuse into continuous interspaces.
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    Unique sensory endings in rat muscle spindles (1973)
    Springer
    Cell & tissue research 136 (1973), S. 511-520 
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    ISSN: 1432-0878
    Keywords: Muscle spindle ; Sensory ending ; Rat ; Development ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary A fine structural study of sternothyroid muscle spindles of young adult rat demonstrates the rare occurrence of unique nerve endings. These endings are situated in the juxta-equatorial region of nuclear-bag fibers, adjacent to the annulo-spiral sensory endings. They consist of a bundle of terminal axons less than 0.3 μ in diameter and appear to be disposed nearly longitudinally to the axis of the intrafusal fibers. Whereas, the annulo-spiral endings consist of a single axon, coiling around the intrafusal fibers. Transverse sections of these muscle spindles reveal these unique endings scattered around the muscle fibers, fitting into depressions on their surface. The innermost axons directly face the muscle surface and are separated by a narrow gap less than 200 Å in width. No Schwann cell process appears to be associated with these endings. From their unique multi-axonal composition, these endings are termed “bundled endings”. Investigations of developing muscle spindles show the occasional presence of a similar multi-axonal composition of sensory endings in perinatal rats. It is suggested that “bundled endings” are sensory in nature, carrying an immature feature over to adult life.
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    URL: http://dx.doi.org/10.1007/BF00307367
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    An electron microscopic study of macroglia and microglia in the lateral funiculus of the developing spinal cord in the fetal monkey (1973)
    Springer
    Cell & tissue research 140 (1973), S. 145-167 
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    ISSN: 1432-0878
    Keywords: Macroglia ; Microglia ; Spinal Cord ; Monkey ; Development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary An electron-microscopic study has been made of the glial cells in the developing lateral funiculus of the cervical spinal cord in fetal rhesus monkeys. The various macroglial cell types, their precursor cells, and microglia are discussed in detail. An astrocytic lineage is proposed in which glioblasts present in the lateral funiculus give rise to astroblasts that then develop into mature astrocytes. Oligoblasts apparently migrate into the lateral funiculus as such and develop into active oligocytes. The active oligocytes become most predominant during the initial stages of myelinogenesis and are in direct continuity with developing myelin. The active oligocytes develop into mature oligocytes after myelination is completed. Microglia cells are present throughout development as three forms; resting microglia, globose microglia, and active microglia. The globose and active microglia predominates at specific times early in development when degeneration of apparent neuronal processes is taking place. The microglia cells are characterized by dense nuclear chromatin clumps, lipid inclusion bodies, dense vesicles, and, often, intracellular debris.
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    The development of synapses in vitro between previously dissociated chick spinal cord neurons (1973)
    Springer
    Cell & tissue research 140 (1973), S. 203-216 
    Details
    ISSN: 1432-0878
    Keywords: Synapses ; Development ; Chick embryo ; Cell culture ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The formation and development of synaptic contacts between dissociated chick spinal cord neurons has been investigated. By the 6th day in vitro “immature” profiles with few vesicles were observed. By 14–18 days “mature” types with numerous vesicles were found, indistinguishable from those of newly hatched chick spinal cord. After this period degeneration occurred, and was especially marked in the post-synaptic element. Such degeneration could be postponed by the addition of small numbers of somatic muscle cells. The Kanaseki and Kadota (1969) technique was applied to the study of coated vesicles at various stages of synaptic development.
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    Demonstration of the granular layer and the fate of the hyaline layer during the development of a sea urchin (Lytechinus variegatus) (1985)
    Springer
    Cell & tissue research 239 (1985), S. 455-458 
    Details
    ISSN: 1432-0878
    Keywords: Development ; Sea urchin ; Hyaline layer ; Granular layer ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Employing electron-microscopic methods that help retain polyanionic materials, we describe the extracellular coverings of a sea urchin (Lytechinus variegatus) throughout ontogeny. The surface of the embryo is covered by a two-layered cuticle (commonly called the hyaline layer), which in turn is covered by a granular layer. The granular layer is retained after addition of alcian blue to the fixative solutions, and has not been previously described for any sea urchin. After hatching, the granular layer disappears, but the hyaline layer continues to cover most of the larval surface until settlement and metamorphosis. A few days before metamorphosis, the hyaline layer lining the vestibular invagination of the competent pluteus larva is replaced by a three-layered cuticle resembling that of the adult sea urchin. The hyaline layer covering the rest of the larva is evidently lost at metamorphosis during the involution of the general epidermis.
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    URL: http://dx.doi.org/10.1007/BF00218028
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    Effects of colchicine and vinblastine on neurotubules of the sciatic nerve and cholinesterases in the developing myoneural junction of the rat (1973)
    Springer
    Cell & tissue research 142 (1973), S. 193-204 
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    ISSN: 1432-0878
    Keywords: Neuromuscular junction ; Development ; Cholinesterases ; Axonal transport, Neurotubules, Colchicine, Vinblastine ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Colchicine (0.1 M) or vinblastine (0.01 M) was locally applied on the sciatic nerves of newborn rats. Both colchicine and vinblastine caused reversible disappearance of axonal neurotubules and appearance of increased amounts of neurofilaments at the site of application. Subsequent morphogenesis of myoneural junctions in the tibialis anterior muscle was studied after histochemical demonstration of acetylcholinesterase (AChE; E.C. 3.1.1.7) and non-specific cholinesterase (Ns. ChE; E.C. 3.1.1.8) activity in the myoneural area. Development of the postsynaptic muscle plasma membrane of the myoneural junction was arrested in the ipsilateral, but not in the contralateral control side, for a period of about three weeks following treatment with the test substances. After this delay the myoneural morphogenesis continued normally and neurotubules were seen in the axoplasm. Since disruption of neurotubules is likely to cause blockage of the intratubular axoplasmic transport system, it seems possible that the neurotrophic influence responsible for the development of the postsynaptic muscle membrane is mediated through a secretory product transported along axons intratubularly to the nerve endings.
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    A light and electron microscopic study of the pre- and postnatal development and secretory differentiation of the pars tuberalis of the rat hypophysis (1973)
    Springer
    Cell & tissue research 142 (1973), S. 347-365 
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    ISSN: 1432-0878
    Keywords: Pars tuberalis ; Rat ; Development ; Secretion ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The development of the pars tuberalis was studied in the rat fetus from 13 days of gestation to 6 weeks after birth. After the closure of Rathke's pouch, the pars tuberalis anlage is clearly distinguishable from the anlagen of the partes intermedia and distalis. It comprises the entire basal portion of the adenohypophysial anlage; the limit between the anlagen of the pars tuberalis and the pars distalis is defined by Atwell's recess, i.e. the pathway taken by the hypophysial vessels coming from the vascular plexus of the median eminence. At 14 days the pars tuberalis cells are characterized by the presence of glycogen which persists in the adult. Their secretory differentiation (elaboration of granules with a diameter of 100–120 nm) is obvious at 15 days of gestation. It therefore, clearly precedes that of the other hypophysial cell types. Its functional differentiation takes place well before its adhesion to the primary vascular plexus of the portal system. Cystic formations appear just before birth in the pars tuberalis, much later than those of the pars distalis. These observations on the development of the pars tuberalis, together with previous observations on the adult PT in various species, showing that the specific glandular cells of the pars tuberalis are cytologically different from all known adenohypophysial cell types, seem to indicate a specific endocrine function of this lobe.
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    Hox genes in digit development and evolution (1999)
    Springer
    Cell & tissue research 296 (1999), S. 19-25 
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    ISSN: 1432-0878
    Keywords: Key wordsHoxA ; HoxD ; Limb ; Development ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Homeobox genes located in the 5’ part of the HoxA and HoxD complexes are required for proliferation of skeletal progenitor cells of the vertebrate limb. Specific combinations of gene products determine the length of the upper arm (genes belonging to groups 9 and 10), the lower arm (groups 10, 11 and 12) and the digits (groups 11, 12 and 13). In these different domains, individual gene products quantitatively contribute to an overall protein dose, with predominant roles for groups 11 and 13. Quantitative reduction in the gene dose in each set results in truncations of the corresponding anatomical regions. The physical order of the genes in the HoxA and HoxD complexes, as well as a unidirectional sequence in gene activation, allow for completion of the process in a precise order, which in turn makes possible the sequential outgrowth of the respective primordia. While the skeletal patterns of upper and lower limb are relatively stable throughout the tetrapods, more variation is seen in the digits. Molecular analysis of the underlying regulatory processes promises further exciting insights into the genetic control of development, pathology and the course of evolution.
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    From head to toe: conservation of molecular signals regulating limb and craniofacial morphogenesis (1999)
    Springer
    Cell & tissue research 296 (1999), S. 103-109 
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    ISSN: 1432-0878
    Keywords: Key wordsgli3 ; Ωtalpid ; extra-toes ; Sonic hedgehog ; Retinoic acid ; Development ; Birth defects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Recent evidence indicates that many molecules involved in generating and patterning the limbs also play a role during craniofacial morphogenesis. On the surface, this is an unexpected finding given that these regions of the body have separate evolutionary origins, are composed of different embryonic tissues, and are quite dissimilar in their anatomy. Results from several experiments involving Sonic hedgehog and retinoic acid point to a remarkable conservation of the signaling pathways mediated by these morphogens across multiple organ systems. Moreover, mutants such as the extra-toes and doublefoot mouse, and the talpid chicken also provide insights on common developmental processes that underlie the formation of the limbs and face. The identification of highly conserved aspects of morphogenesis is important for understanding fundamental mechanisms of development, as well as for revealing the common denominator of countless birth defects and providing new strategies for their prevention and cure.
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    Structure and development of the auditory system in the prothoracic leg of the cricket Teleogryllus commodus (walker) (1974)
    Springer
    Cell & tissue research 147 (1974), S. 313-324 
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    ISSN: 1432-0878
    Keywords: Chordotonal organ ; Teleogryllus commodus ; Hearing ; Structure ; Development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The anatomical development of the tympanal organ, the tracheal system and the tympana of Teleogryllus commodus is described. The tympanal organ is undifferentiated until instar 3 when the first scolopales appear. The organ develops in a proximo-distal direction but the more distal groups begin to form before the proximal groups are complete. All groups of scolopidia are represented in instar 7 but numbers of scolopidia continue to increase until the adult stage. Scolopales and scolopale cells are first formed at less than adult size and increase in size during subsequent instars. The subgenual organ is present in instar 1 and is complete in instar 4. The posterior and anterior tympanal trachease develop respectively from the tracheal trunk and tracheal branch, which are present from instar 2. These remain as simple, unconnected tubes until instar 7 and begin to show the adult form during instars 8 and 9, finally enlarging in conjunction with the tympana at the last two moults. The tympana first appear as hairless areas of cuticle in the larval stages: the posterior tympanum in instar 8 and anterior tympanum in instar 10, but the translucent appearance of the adult tympana is not present before the final moult.
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    Development of Xenopus laevis skin glands producing 5-hydroxytryptamine and caerulein (1989)
    Springer
    Cell & tissue research 258 (1989), S. 483-489 
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    ISSN: 1432-0878
    Keywords: Development ; Skin glands ; Peptides ; Metamorphosis ; Xenopus laevis (Anura)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The granular glands in Xenopus laevis skin are known to contain large quantities of biogenic amines and bioactive peptides which closely resemble mammalian brain-gut peptides. We studied the development of glands producing 5-hydroxytryptamine (5-HT) and caerulein using immunohistochemistry, HPLC-fluorometric systems and RIA. The immunoreactivities of 5-HT and caerulein were first detected in the spherical gland rudiments in the stratum spongiosum at St. 58 (Nieuwkoop and Faber stage), or at the beginning of metamorphosis. Both immunoreactivities appeared in the same rudiment at the same time. Some of the gland rudiments have a small lumen filled with both immunoreactive materials at St. 58–59. During the rest of the metamorphic period, the glands grow in size, accumulating immunoreactive materials in the lumen. The concentrations of 5-HT and caerulein in the skin of tadpoles were below 1 ng per mg wet tissue at St. 58–59, increased as metamorphosis proceeded and reached 63 and 134 ng per mg wet tissue at St. 66, or at the end of metamorphosis, respectively. The amphibian granular glands where large quantities of biogenic amines and hormone-like peptides are rapidly synthesized may provide a useful model for the study of the development of amine- and peptide-producing cells including neurons and paraneurons.
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    Morphogenesis of tight junctions in the peritoneal mesothelium of the mouse embryo (1979)
    Springer
    Cell & tissue research 198 (1979), S. 247-260 
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    ISSN: 1432-0878
    Keywords: Tight junctions ; Development ; Mesothelium ; Mouse embryo ; Freeze-fracture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The peritoneal mesothelium of mouse embryos (12 to 18 day of gestation) was studied by freeze-fracture and in sections in order to reveal the initial formation of the tight junctions. Freeze-fracture observations showed three types of tight junctions. Type I consists of belt-like meshworks of elevations on the P face and of shallow grooves on the E face. No tight junctional particle can be seen either on the elevations or in the grooves. Type II shows rows of discontinuous particles on the elevations on the P face. Type III consists of strands forming ridges on the P face. On the E face, the grooves of Type II and III appear to be narrower and sharper than those of Type I. Quantitatively, Type I junctions are most numerous during the early stages (day 12–13) of embryonic development, while Type III junctions become more common in the later stages, and are the only type seen by day 18. Observations on sections, however, fail to distinguish between the three types. The results suggest that an initial sign of tight junction formation is close apposition of the two cell membranes in the junctional domain, without tight junctional particles. Later, the particles appear to be incorporated in the tight junctions and the strands form by fusion of the particles.
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    Development of the axon cap neuropil of the Mauthner cell in the goldfish (1984)
    Springer
    Cell & tissue research 237 (1984), S. 49-55 
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    ISSN: 1432-0878
    Keywords: Axon ; Synapses ; Medulla oblongata ; Gold-fish ; Development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Development of the axon cap neuropil of the Mauthner neuron in post-hatching larval goldfish brains was observed electron-microscopically. The axonal initial segment of newly hatched (day-4) larvae is completely covered with synaptic terminals containing clear spherical synaptic vesicles. Profiles of thin terminal axons, the spiral fibers, containing similar synaptic vesicles, rapidly increase in number around the initial segment and form glomerular neuropil similar to the central core of the adult axon cap by day 7. Three types of synapses are formed in the core neuropil. Bouton-type synapses contacting the initial segment are most abundant in day-4 to-14 larvae; they decrease thereafter and are rare on the distal half of the initial segment of day-40 larvae. Asymmetric axo-axonic synapses are commonly observed between spiral fibers in the core neuropil of day-7 to -19 larvae, but become fewer by day 40. Unique symmetrical axo-axonic synapses showing accumulation of synaptic vesicles on either side of apposed membrane thickenings first appear in day-14 core neuropil, gradually increase in number, and become the predominant type in day-40 core neuropil. Thick myelinated axons, which lose their myelin sheaths in the glial cap cell layer, start to penetrate into the axon cap on day 10. They gradually increase in number and form the peripheral part of the axon cap together with the cap dendrites, which finally grow into the axon cap from the axon hillock region of the Mauthner cell by day 40.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00229199
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    Topographical and developmental studies on target sites of 1,25 (OH2) vitamin D3 in skin (1984)
    Springer
    Cell & tissue research 238 (1984), S. 489-496 
    Details
    ISSN: 1432-0878
    Keywords: Vitamin D ; Skin ; Autoradiography ; Hair ; Development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Tritium-labeled 1,25 (OH2) vitamin D3, when injected into vitamin D-deficient adult and pregnant rats is concentrated and retained strongest in nuclei of cells in the outer root sheath of the hair, followed by the stratum granulosum, spinosum, and basale of the epidermis. In the hair follicle, in addition to the most heavily labeled outer root sheath, nuclear labeling exists also in cells of the hair bulb and of the inner root sheath, as well as in basal cells of the sebaceous gland. In contrast, cells of the dermal papilla and the connective tissue of the dermis are generally unlabeled, except for labeled cells in the outer connective tissue sheath at the infundibulum of vibrissae of 20-day fetal rats and a few scattered labeled cells in the dermis, probably macrophages. In the developing hair, in 18- and 20-day fetal rats, a distinct topographic pattern of labeled cells can be seen, which is characteristic of the different stages of hair follicle development. In the hair germ, heavily labeled cells appear first in the stratum spinosum. In the hair peg, they remain in this position in its juxtaepidermal portion; however, when a dermal papilla develops, heavily labeled cells assume a marginal position. This suggests a sequential epidermal-epidermal and mesenchymal-epidermal receptor induction. Injection of tritium labeled 25 (OH) vitamin D3 did not show nuclear concentration in these tissues and excess unlabeled 25 (OH) vitamin D3 — unlike excess 1,25 (OH2) vitamin D3 — did not prevent nuclear uptake of tritium labeled 1,25 (OH2) vitamin D3. The results indicate differential effects of 1,25 (OH2) vitamin D3 on different structures in the epidermis and dermis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00219863
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  • 95
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    Origin of the glial processes responsible for the spontaneous postnatal phagocytosis of boutons on cat spinal motoneurons (1978)
    Springer
    Cell & tissue research 189 (1978), S. 203-217 
    Details
    ISSN: 1432-0878
    Keywords: Astrocytes ; Development ; Phagocytosis ; Neuroplasticity ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Previous studies have demonstrated that astrocyte processes are responsible for a spontaneously occurring phagocytosis of boutons on cat spinal motoneurons during the second postnatal week. In the present investigation, the astrocytes and the astrocyte processes in contact with the motoneurons were studied qualitatively and quantitatively during the early postnatal period. It could be concluded that the cells responsible for the phagocytosis of boutons are immature astrocytes. These cells were present not only during the period of phagocytosis but also prior to this period. The type of process responsible for the phagocytosis was present not only during the period of phagocytosis but also prior to and after that period although the relative contribution of such processes to the glia-covered membrane area of the motoneurons was reduced in the older animals. On the basis of these results, the possible specificity of the immature astrocyte as the element responsible for the phagocytosis of boutons during normal development is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00209270
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  • 96
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    Ultrastructural study of microsporidian development (1970)
    Springer
    Cell & tissue research 105 (1970), S. 33-54 
    Details
    ISSN: 1432-0878
    Keywords: Microsporidian ; Development ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Vegetative growth of Nosema sp. occurs within the gut submucosal cells of Callinectes sapidus. Vegetative cell morphology is dominated by profiles of endoplasmic reticulum, numerous free ribosomes and aggregates of vesicles enclosed by a membranous sac. The dikaryotic vegetative cell is the earliest stage found in the target area for sporogenesis, the sarcoplasm of the striated muscle cell. The next obvious stage is the sporoblast mother cell; it undergoes karyokinesis without breakdown of the nuclear envelope. Intranuclear mitotic microtubules extend from the chromosomes to the intact nuclear envelope. After repeated nuclear divisions, the sporoblast mother cell undergoes delayed cytokinesis and a series of sporoblast progeny develops. The polar filament is the first visually apparent system to develop during sporogenesis. It appears to be of dual origin: (1) the central core component is condensed in Golgi-like saccules, and (2) the envelopes around the core originate from the endoplasmic reticulum. The polaroplast, which forms after early polar filament development, appears to originate as an elaboration of the endoplasmic reticulum.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00340563
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  • 97
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    Midbody sealing after cytokinesis in embryos of the sea urchin Arabacia punctulata (1985)
    Springer
    Cell & tissue research 240 (1985), S. 287-292 
    Details
    ISSN: 1432-0878
    Keywords: Cytokinesis ; Dye coupling ; Development ; Embryo ; Microinjection ; Sea urchin Arabacia punctulata
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Cytokinesis consists of a contractile phase followed by sealing of the connecting midbody to form two separated cells. To determine how soon the midbody sealed after cleavage furrow contraction, the fluorescent dye Lucifer Yellow CH(457.3 M.W.) was microinjected into cells at various intervals after cleavage had begun. Mitotic PtK2 cells were recorded with video-microscopy so that daughter cells in the epithelial sheet could be identified for several hours after cell division. One daughter cell of each pair followed was microinjected to determine whether the dye diffused into the other daughter cell. For intervals up to four hours after the beginning of cytokinesis, diffusion took place between daughter cells. After this time the dye did not spread between daughter cells. In sea urchin blastomeres of the first, second and third divisions, Lucifer Yellow passed between daughter blastomeres only during the first 15 min after cytokinesis. If one cell of a two-cell, four-cell or eight-cell embryo was microinjected more than 15 min after the last cleavage, the dye remained in the injected cell and was distributed to all progeny of that cell, resulting in blastulae that were either one-half, one-quarter or one-eighth fluorescent, respectively. Thus, although cleavage furrow contraction takes approximately the same amount of time in sea urchin blastomeres and PtK2 cells, the time of midbody sealing differs dramatically in the two cell types. Our results also indicate the importance of knowing the mitotic history of cells when injecting dyes into interphase cells for the purpose of detecting gap junctions.
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    URL: http://dx.doi.org/10.1007/BF00222337
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  • 98
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    Interconnections between the stereovilli of the fish inner ear (1986)
    Springer
    Cell & tissue research 246 (1986), S. 447-453 
    Details
    ISSN: 1432-0878
    Keywords: Vestibular organ ; Hair cells ; Stereocilia ; Development ; Differentiation ; Teleosts (Rutilus rutilus)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The maculae utriculi and sacculi of the inner ear from the European roach (Rutilus rutilus) were investigated by transmission electron microscopy. The stereovilli of peripherally and centrally located sensory cells differ in several features that suggest a developmental gradient. The stereovilli of the peripheral sensory cells, shown to be differentiating cells by other research groups, are short and less steeply graded in height than in central hair cells. All stereovilli in both kinds of hair bundles are interconnected. In the central bundles of stereovilli basal, tip, and vertical connectors are separated by unconnected regions. In contrast, filaments and sometimes other additional structures connect the stereovilli of peripheral bundles over their entire length, but vertical connectors are usually absent. Osmiophilic material occurring inside peripheral stereovilli is interpreted to be monomeric actin. Central and peripheral hair bundles also differ in their reaction to ruthenium red and cationized ferritin. Only the stereovilli of the central cells can be fused by these polycations. Ruthenium red also discriminates between supporting and sensory cells indicating differences in amount or distribution of extracellular material. Hair bundles, intermediate in properties and position between central and peripheral sensory cells, were also found, so that it became possible to propose a scheme of developmental steps leading from microvilli or microvillus-like stereovilli to the fully differentiated hair bundle.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00215907
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  • 99
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    Prenatal and early postnatal development of the glial cells in the median eminence of the rat (1980)
    Springer
    Cell & tissue research 211 (1980), S. 117-137 
    Details
    ISSN: 1432-0878
    Keywords: Eminentia mediana ; Neurohypophysis ; Development ; Pituicytes ; Tanycytes ; Astrocytic tanycytes ; Oligodendrocytes ; Astrocytes ; Microglia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The development of the glial cells of the rat median eminence (ME), including the supraependymal cells, was investigated from embryonic day (ED) 14 through postnatal day (PD) 7, and pituicyte development from ED 12 through ED 17. The anlage of the ME and neurohypophysis shows a neuroepithelial-like structure at ED 12. From ED 13 to 15, the cells of both regions start to differentiate. At the ultrastructural level, only one cell type appears. At the beginning of ED 16, glioblasts of the oligodendrocyte and astrocyte series migrate laterally (from the region of the arcuate nucleus) into the ME. Also at this time the first distinctive structural features appear in the neurohypophysial anlage, the cells of which later develop into pituicytes. Starting at ED 18, tanycytes and astrocytic tanycytes arise in the ME from local glial cells, and somewhat later oligodendroblasts and astroblasts are formed from immigrant glioblasts. Due to their common features, the pituicytes, tanycytes and astrocytic tanycytes apparently represent different forms of the same parent cell type. Microglial and supraependymal cells are first seen at ED 12. Initially, they resemble the prenatal phagocytic connective tissue cells and mature in the fetus into typical electron-dense microglia and macrophage-like supraependymal cells. Both cell types are apparently of mesodermal origin. The microglial elements of the ME probably migrate from the mesenchyma through the basement into the nervous tissue. The intraventricular macrophages of the infundibular region may originate from microglia, epiplexal cells and subarachnoid macrophages.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00233728
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  • 100
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    Postnatal development of somatotrophs and mammotrophs in the pars distalis of the C57BL mouse (1980)
    Springer
    Cell & tissue research 211 (1980), S. 441-448 
    Details
    ISSN: 1432-0878
    Keywords: Somatotroph ; Mammotroph ; Development ; Mouse ; Pituitary
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The pars distalis of the pituitary gland of the C57BL mouse was studied by means of electron microscopy during postnatal stages of males ranging in age from newborn through 24 days, with particular emphasis on the somatotrophs and mammotrophs. During this period, growth curves were plotted in order to correlate postnatal growth patterns with the state of differentiation of the somatotrophs in the pars distalis. In the newborn, the somatotrophs show well developed organelles, including rough endoplasmic reticulum and Golgi complexes. These cells are not as densely packed with granules as the adult somatotrophs; however, from days 5 through 24, they show a progressive accumulation of granules. Although mammotrophs are scarce in the newborn, they are readily distinguishable in the pars distalis at 5 days. Male mice in small litters show a progressive increase in body weight between birth and 11–12 days, at which time the rate slackens until 18–19 days when the rate again increases. Growth curves for mice from large litters are similar to those from smaller litters, except that the transitory decrease in rate is more prominent.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00234398
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