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  • Analytical Chemistry and Spectroscopy  (1,826)
  • Life and Medical Sciences  (1,362)
  • 2000-2004
  • 1980-1984  (3,188)
  • 1975-1979
  • 1960-1964
  • 1925-1929
  • 1984  (1,650)
  • 1981  (1,538)
Collection
Publisher
Years
  • 2000-2004
  • 1980-1984  (3,188)
  • 1975-1979
  • 1960-1964
  • 1925-1929
Year
  • 101
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: With the use of rabbit antisera against crustacean hyperglycemic hormone (CHH), it is possible to describe a distinct immunopositive reaction in a group of neurosecretory cells in the medulla terminalis ganglionic X-organ2 (MTGX2), in the MTGX-sinus gland tract, and in a considerable part of the sinus gland from several species of prawns belonging to the Palaemonidae. By introductory studies on the CHH system in Palaemon serratus, we can postulate a sequence in the activity cycle of the CHH-producing cells on the basis of differences in staining intensity of the immunoreaction and such morphometric parameters as cellular and nuclear diameter. By studying the CHH-producing system in combination with variations in the glucose level of the blood, an “inverse relationship” is observed between the number of immunoreactive cells and the blood glucose level during different periods of the year as well as during different stages of the molting cycle. A “shift in phase” of this correlation during the diurnal cycle suggests that several rhythmical phenomena may play a role in the regulation of glycemia in Crustacea.
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  • 102
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    Journal of Morphology 182 (1984), S. 115-123 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A large mechanosensory campaniform sensillum (LCS) is found close to the flagellum/pedicellus joint in the antennae of the blowfly Calliphora erythrocephala. The LCS possesses a single sensory cell, enveloping cells and a cuticular stimulus-conducting structure. The distal part of the sensory process is developed as a tubular body and is connected to the two parts of the stimulusconducting apparatus. The sensory cell is characterized by the complete absence of ciliary structures in the transition zone between dendrite and sensory process.
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  • 103
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    Journal of Morphology 182 (1984), S. 95-113 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A three-dimensional muscle model with complex geometry is described and tested against experimental data. Using this model, several muscles were constructed. These muscles have equal optimum length but differ in architecture. The force exerted by the constructed muscles, in relation to their actual length and velocity of shortening, is discussed. Generally speaking, the constructed muscles with considerable pennation have great fiber angles, a great physiological cross section, a narrow active and steep passive length-force relation, and a low maximal velocity of shortening. The maximal power (force times velocity) delivered by the constructed muscles is shown to be almost independent of the architecture of the muscles. The steepness of the passive length-force relation is determined mainly by the shortest fibers within the group of constructed muscles, wheras maximal velocity of shortening and the width of the active length-force relation are determined mainly by the longest fibers.The validity of the three-dimensional muscle model with respect to some morphological and functional characteristics is tested. Length-force relations of constructed muscles are compared with the actual length-force relations of mm. gastrocnemii mediales and mm. semimembranosi of male Wistar rats. Moreover, actual fiber angle, fiber length, and muscle thickness of three mm. gastrocnemii mediales are compared with values found for constructed muscles. It is concluded that the three-dimensional muscle model closely approximates the actual muscle form and function.
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  • 104
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    Journal of Morphology 182 (1984), S. 125-136 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Horseradish peroxidase histochemical studies of afferent and efferent projections of the trigeminal nerve in two species of chondrostean fishes revealed medial, descending and ascending projections. Entering fibers of the trigeminal sensory root project medially to terminate in the medial trigeminal nucleus, located along the medial wall of the rostral medulla. Other entering sensory fibers turn caudally within the medulla, forming the trigeminal spinal tract, and terminate within the descending trigeminal nucleus. The descending trigeminal nucleus consists of dorsal (DTNd) and ventral (DTNv) components. Fibers of the trigeminal spinal tract descend through the lateral alar medulla and into the dorsolateral cervical spinal cord. Fibers exit the spinal tract throughout its length, projecting to the ventral descending trigeminal nucleus (DTNv) in the medulla and to the funicular nucleus at the obex. Retrograde transport of HRP through sensory root fibers also revealed an ascending bundle of fibers that constitutes the neurites of the mesencephalic trigeminal nucleus, cell bodies of which are located in the rostral optic tectum. Retrograde transport of HRP through motor root fibers labeled ipsilateral cells of the trigeminal motor nucleus, located in the rostral branchiomeric motor column.
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  • 105
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    Journal of Morphology 182 (1984), S. 153-168 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Two types of nerve cells, sensory and ganglion cells, were identified in the epidermis of the hypostome of Pelmatohydra robusta by light and electron microscopy. In the study of distribution of these cells, the presence of a circumhypostomal nerve ring in the epidermis was revealed, although hydras have been considered to possess only a diffuse nervous system or socalled nerve net. The nerve ring, which encircled the hypostome, was constituted by several clusters of ganglion cells, thick bundles of many neurites connecting these clusters, and a small number of individual ganglion cells located along the bundles. In the nerve ring, some of the lamellae protruding from the ganglion cells were frequently myelinated and wrapped the cell bodies of neighboring ganglion cells, and other lamellae were arranged in concentric circles.
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  • 106
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    Journal of Morphology 182 (1984), S. 137-152 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The epithelium of the posterior intestine and hindgut of recently metamorphosed adult lampreys (Petromyzon marinus L.) prior to and during spontaneous feeding was examined using light and electron microscopy. These two regions differ slightly in their general morphology but possess the same mucosal cell types. Included are caveolated absorptive and mucous cells, which are not present in more cephalic regions of the intestine, and ciliated and enteroendocrine cells. During feeding, the caveolated cells undergo dramatic transformation in their structure, namely, through the acquisition of numerous heterophagic vacuoles. Due to their morphology and to the fact that there are low amounts of lipid, it is suspected that caveolated cells are primarily involved in the absorption of protein components from the ingested host blood and body fluids. Iron in caveolated cells may result from the degradation of ingested heme or reflect the excretion of bile products at this location in the intestine. Mucous cells are likely responsible for lubrication of the luminal surface and may be important as a stem cell for the mucosal epithelium.
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  • 107
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    Journal of Morphology 182 (1984), S. 169-178 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This investigation describes the morphogenesis of the type I pneumocyte from the neonatal stage to the age of 3 months. Cells lining subpleural air spaces were photographed from electron microscopic serial sections and a three-dimensional representation of each cell was obtained by transferring the contours of the cell membranes from micrographs to transparent plastic sheets which were then spaced to scale and stacked. The portion of the reconstructed cell surface taking part in the formation of the blood-airbarrier increased extensively in postnatal stages when compared with reconstructed cells of prenatal stages. Reconstructed cell-surface irregularities decrease during distension. A cytoplasmic plate seen in the last stage studied may represent a forming alveolar pore.
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  • 108
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    Journal of Morphology 182 (1984), S. 179-196 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Three hypothetical models of tongue movement of the walrus during suction feeding are examined. These models encompass the entire range of simple tongue retraction movements possible by examining 1) movement of the tongue directly to the rear following the curvature of the palate, 2) to the rear and ventrally in a straight line, and 3) ventrally in a straight line. The percent of muscular force available from the hyoglossus, genioglossus, and styloglossus that could be applied toward retraction as predicted by each model is calculated. The resistance that the tongue would provide during retraction is calculated using projected tongue areas and is combined with the above data from the muscles to provide an estimate of the percent of the total available force that is needed to retract the tongue for each model. A separate examination of the direction of tongue-induced wear striations on the palatal and lingual aspects of the teeth is used to help support or reject the three models.The model where the tongue is moved directly to the rear is supported by studies of both muscle force and tooth wear. In the mammalian groups that were compared to the walrus, there is a great deal of interspecific variation in movements of the tongue during suction feeding; no two groups can be considered to have identical stereotyped tongue movements.
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  • 109
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    Journal of Morphology 182 (1984), S. 221-225 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The retina of the chick contains retinal cells of a morphology very similar to that of the horizontal cells, but the perikarya, axons, and axon terminals lie in the inner plexiform layer. The discovery of this neuronal ectopia appears to support the idea that some horizontal and amacrine cells derive from a common, freely migrating cell.
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  • 110
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    Journal of Morphology 182 (1984) 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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  • 111
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    Journal of Morphology 182 (1984), S. 227-244 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The cranial and cervical osteology of the European oystercatcher, Haematopus ostralegus L. is completely described from both whole skeletons and spirit specimens. Contrary to previous reports, the postorbital ligament shows variability in bifurcation and attachment, with the posterior branch, where present, attaching either to the suprameatic process or the zygomatic process. In addition, the quadrate ligament, which had been described as originating from the suprameatic process, appears instead to attach to the zygomatic process in some specimens. The caudal mandibular fenestra, earlier considered absent in oystercatchers, is present in all specimens examined. The cranium is additionally distinguished by a number of features which may be unique to oystercatchers. A fourth, previously unrecorded, division of the maxillopalatine strut is present, while the palatine process of the premaxilla is reduced to a thickening along the edge of the premaxillary process of the palatine. The distinctiveness of the oystercatcher cranium is particularly evident in the area of the quadratomandibular articulation, which possesses features potentially important for stabilizing the joint. A deep retroarticular notch is present, guiding a large medial jugomandibular ligament along the posterior margin of the articulation. A lateral mandibular tuberosity, which is received dorsally by an emargination of the jugal arch and quadrate, may act as an osteological brace, preventing posterior shifting of the closed mandible. The 15 cervical vertebrae are divided on the basis of structural criteria into three sections.
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  • 112
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    Journal of Morphology 182 (1984), S. 197-219 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Many climbing mammals are able to reverse normal hind foot posture to effect the grip necessary to descend headfirst or to hang upside down. Such hind foot reversal is known in sciurids, procyonids, felids, viverrids, tupaiids, prosimians, and marsupials. The joint movements involved, however, have never been documented unequivocally although various interpretations (some contradictory) have been made. We report here radiographic data from species of the genera Didelphis, Felis, Nasua, Nycticebus, Potos, Sciurus, and Tupaia. In the six eutherians studied, three joints are involved, and there is a common pattern in the mechanism: crurotalar plantarflexion, subtalar inversion, and transverse tarsal supination. Hind foot reversal represents the development of an unusual degree of excursion at these joints, rather than the appearance of any new type of movement. In Didelphis the mechanism is quite different: a bicondylar, spiral tibiotalar joint is the principal site of inversion/abduction movements. This specialization is characteristic of didelphids and phalangerids, and occurs in the extinct multituberculates as well; it is not found in macropodids (which are like eutherians in crurotalar joint structure) or other marsupial families. This diversity in pedal structure and function is evidently the result of parallel evolution from the type of tibiotalar joint of cynodonts and early mammals. In Morganucodon the bulbous, hemispheroidal proximal surface of the talus bears two tibial facets. These facets are represented in didelphids and multituberculates as sulci, whereas in macropodids and eutherians they developed as the proximal and medial surfaces of the talar trochlea. Among living mammals, the primitive hemispheroidal joint is retained among monotremes as a ball and socket joint.
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  • 113
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    Journal of Morphology 182 (1984), S. 245-255 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The sequence of appearance of the 17 different skull bones in the oriental fire-bellied toad, Bombina orientalis, is described. Data are based primarily on samples of ten or 11 laboratory-reared specimens of each of 11 Gosner developmental stages (36-46) representing middle through late metamorphosis. Ossification commences as early as stage 37 (hind limb with all five toes distinct), but the full complement of adult bones is not attained until stage 46 (metamorphosis complete). Number of bones present at intermediate stages is poorly correlated with external morphology. As many as four Gosner developmental stages elapse before a given bone is present in all specimens following the stage at which it may first appear. The modal ossification sequence is frontoparietal, exoccipital, parasphenoid, septomaxilla, premaxilla, vomer, nasal, maxilla, angulosplenial, dentary, squamosal, quadratojugal, pterygoid, prootic, interfrontal, sphenethmoid, and mentomeckelian. Most specimens are consistent with this sequence, despite the poor correlation between cranial ossification and external development as assayed by Gosner stage.The timing of cranial ossification in Bombina orientalis differs in many respects from that described for two other, distantly related anurans, the leopard frog (Rana pipiens) and the western toad (Bufo boreas). These include the total number and sequence of appearance of bones, and the timing of ossification relative to the development of external morphology. Interspecific variation may reflect differences in the timing of the tissue interactions known to underlie skeletal differentiation and evolution.
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  • 114
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    Journal of Morphology 182 (1984), S. 257-277 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The ultrastructure of the Malpighian tubules, ileum, rectum, anal canal, and anal papillae of larvae of the mosquito Culiseta inornata was examined. The Malpighian tubules, rectum, and anal papillae have many of the ultrastructural features characteristic of ion transport tissues, i.e., elaboration of the basal and apical membranes and a close association of these membranes with mitochondria. The Malpighian tubules possess two cell types, primary and stellate. The larval rectum of C. inornata is composed of a single segment containing a homogenous population of cells. In this respect, the larval rectum of C. inornata is distinct from that of saline-water species of Aedes. The cells in the larval rectum of C. inornata, however, closely resemble those of one cell type, the anterior rectal cells, of the saline-water mosquito Aedes campestris with regard to cell and nuclear size, the percentage of the cell occupied by apical folds, and mitochondrial density and distribution. No similarities can be found between the rectum of C. inornata and the posterior segment of the saline-water Aedes, which functions as a salt gland. On this basis, we have postulated that the rectum of C. inornata does not function as a site of hyperosmotic fluid secretion. The ultrastructure of the anal papillae of C. inornata is consistent with a role in ion transport. The significance of these findings to comparative aspects of osmoregulatory strategies in mosquito larvae is discussed.
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  • 115
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    Journal of Morphology 182 (1984), S. 279-294 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Among cockroaches in the subfamily of Oxyhaloinae, the adult males produce two essential and successively active chemical signals: the sex pheromone attracting females from a distance secreted by the sternal glands, and the aphrodisiac required for mating which is secreted by the tergal glands. The adult males of the seven species studied, Nauphoeta cinerea, Henschoutedenia flexivitta, Leucophaea maderae, Jagrehnia madecassa, Gromphadorhina portentosa, G. laevigata, and G. chopardi, possess well-developed sternal and tergal glands whose number varies according to the species and methods of mating (three to six sternal glands and four to seven tergal glands). These glands are basically composed of type three glandular units (glandular cell + duct cell) and type 2 cells (modified oenocytes) which exhibit no significant external cuticular modification except for tergite 2 of L. maderae. The extreme variance in development of these glands can be linked to sexual behavior. The hypothesis put forward here is that of a regressive evolution of the tergal glands, related to a modification of the role played by the aphrodisiacs which they secrete.
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  • 116
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    Journal of Morphology 182 (1984), S. 295-305 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The gross morphology and histology of the alimentary tracts of three species of glassy perchlet; Ambassis productus, A. natalensis, and A. gymnocephalus from estuaries on the southeast coast of Africa were investigated. The anatomy of the digestive tracts in all three species was found to be similar. Well-developed dentition and pharyngeal teeth together with a distensible stomach and a low relative gut length (RGL) suggest a predatory and carnivorous habit for all three species.The relative gut lengths of Ambassis species from different estuarine systems are compared‥ Differences in RGL for A. productus and A. natalensis from the Kosi and St Lucia systems with fish from Mdloti estuary are discussed. It is suggested that decreased RGL for fish at Mdloti is attributable to decreased food availability and not to a lack in the calorific content of their diet.Histological investigation revealed the presence of the following regions: a pharynx; an oesophagus; a stomach differentiated into cardiac and pyloric regions; a duodenum or upper intestine; an ileum or lower intestine; and a rectum. Pyloric and rectal sphincters are present. The tunics of the above regions are described. The epithelium of the oesophagus contains taste buds and numerous mucus cells, and varies from stratified anteriorly to simple columnar posteriorly. The muscularis comprises dorsally and ventrally located inner muscle bundles and an outer circular layer. Both layers consist of striated fibres.Gastric glands are present in the mucosa of the cardiac stomach but are absent in the pylorus. Columnar absorbing cells and goblet cells are present in the epithelium of the upper and lower intestine. The rectum is distinguished from the intestine by the proliferation of mucous-secreting cells which are thought to aid defecation.
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  • 117
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    Journal of Morphology 182 (1984), S. 317-337 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Cross sections through the middle segment of the anuran rectus abdominis muscle were analyzed morphometrically at nine stage of development, from early larval life through full maturity. The numbers, sizes, and relative distributions of twitch and slow muscle fibers, newly differentiated fibers, degenerating fibers, and satellite cells were determined at each stage. The data indicate that the muscle increases slowly in size and fiber content during early larval life. New fibers appear to form primarily along the medial margin of the muscle. During mid-larval stages, when thyroid hormone levels are rising, new fibers form throughout the medial portion of the muscle. At a slightly later stage, fibers in the lateral region of the muscle begin to degenerate. Structurally normal presynaptic elements are present on both degenerating fibers and the empty basal laminae of fibers that had been removed by phagocytes. Both fiber formation and fiber loss slow during midmetamorphic climax, at the time when thyroid hormone levels reach a peak in anurans and begin to decline. Degenerating fibers appear within the body of the muscle at the end of metamorphosis. By the end of the second postmetamorphic month, neither degenerating nor newly differentiated fibers are present. The muscle continues to grow through adult life primarily by fiber hypertrophy.
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  • 118
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    Journal of Morphology 182 (1984), S. 307-316 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The adrenergic innervation of structures in the gills of brown and rainbow trout was studied with catecholamine fluorescence histochemistry.In the arterio-arterial vascular pathway, there was an innervation of the afferent and efferent lamellar arterioles, but the afferent and efferent filamental arteries and the secondary lamellae were devoid of any fluorescent nerve fibres. In S. trutta only, there was an additional innervation of the afferent and efferent branchial arteries and the base of the efferent filamental artery.The innervation of the arterio-venous vascular pathway was similar in both trout species. Many fluorescent nerve fibres were found on nutritive arterioles in the gill arch and interbranchial septum, and in the core of each filament between the surface epithelium and the wall of the filament venous sinus. No fluorescent nerve fibres were observed at the origins of the capillaries arising from the efferent filamental artery.The sympathetic nerve supply is provided to the gills mainly through the posttrematic nerve, with an occasional small contribution through the pretrematic nerve.The presence of adrenergic nerves in the gills is discussed in relation to the regulation of blood flow through the arterio-arterial and arterio-venous pathways.
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  • 119
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    Journal of Morphology 182 (1984), S. 339-354 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The presence of both book lungs and a tracheal system in many spiders raises the question of the functional significance of this double respiratory system. The present physiological and morphometric study of the house spider (Tegenaria spp.) reveals that the diffusing capacity (Dto2) of the lungs alone suffices during rest and following exercise to meet measured rates of oxygen consumption (\documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm V}\limits^{\rm.} $\end{document}o2) at driving pressures (ΔPto2) similar to those calculated for vertebrate lungs. During moulting ΔPto2 may rise to more than double the vertebrate values, implying the possible insufficiency of book lungs during this critical life phase. Resting \documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm V}\limits^{\rm .} $\end{document}o2 is greatest (92 mm3/h · g) during the early morning and lowest (66 mm3/h · g) near midday: during moulting \documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm V}\limits^{\rm .} $\end{document}o2 rises to 278.7 mm3/h · g. In spiders recovering from exercise \documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm V}\limits^{\rm .} $\end{document}o2 is consistently greater than during rest: neither value is significantly reduced by blockage of the tracheal stigmas. Regression calculations of morphometric values for a hypothetical 100-mg Tegenaria yield a total lung volume of 0.578 mm3, a pulmonary surface area of 69.8 mm2, and a surface-to-volume ratio of 120.89 mm2/mm3. In spite of the similar thickness of the chitinous and hypodermal components of the air-hemolymph barrier (each ca. 0.2 μm in nonmoulting animals), the low permeability of chitin for oxygen makes this layer the greater barrier to diffusion. For a 100-mg specimen Dto2 is 3.5 mm3/h · torr: similar to that of a turtle (Pseudemys) on a gram-body weight basis.
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  • 120
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    Journal of Morphology 167 (1981), S. 1-12 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: It has recently been shown that the consistency of food significantly affects levels of bone strain in the mandible during mastication (Hylander, '79a). Mandibular bone histology was examined to test the effects of a diet of hard food compared to a diet of soft food in two group of monkeys. One group of rhesus macaques (Macaca mulatta) was fed a diet of commercially prepared hard biscuits. The second group was fed a soft diet the consistency of fudge. Both diets were nutritionally adequate for normal growth and development. As a control for other factors influencing cortical bone structure, fibular morphology was also examined. At the end of the test period, mandibular and fibular tissue samples from the two groups were prepared to determine the amount of secondary Haversian bone present. Mandibular depth at M2 and fibular anteroposterior diameter were also measured and compared between the two dietary groups.The soft-diet monkeys showed low levels of remodeling in their mandibles. There were large patches of unremodeled bone and resorption spaces were common. The hard-diet monkeys exhibited more extensive evidence of secondary Haversian remodeling in their mandibles. The hard-diet monkeys also had deeper mandibles. In contrast, the fibulae from the two groups had similar mean diameters and showed comparable levels of secondary remodeling. We infer that the higher mandibular bone remodeling levels in the hard-diet monkeys represent an adaptive response to remove and replace fatigued mandibular bone due to higher stress levels associated with the ingestion and mastication of hard foods. We also infer that greater depth of the mandible at M2 found in the harddiet group represents an adaptive response to higher stress levels associated with the ingestion and mastication of hard foods.
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  • 121
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    Journal of Morphology 167 (1981) 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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  • 122
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    Notes: The ultrastructure of the supporting cells in the chemoreceptor areas of the tentacles of Pomatias elegans and Helix pomatia is very similar. Complex apical structures are present, and the lateral plasma membrane exhibits three zones: (1) a zone of slight interdigitations; (2) a zone characterized by longitudinal plicae; (3) a zone of basal radiculae. The portions of the sensory cells located within the epithelial layer are accommodated in longitudinal grooves in the supporting cells. However, there are also differences. In Pomatias elegans the apical surface is differentiated into long microvilli that are sometimes dichotomously branched and invested by a surface coat along their entire length. Cytofilia and cilia of the sensory cells pass through this layer of microvilli and surface coat throughout its entire width. In Helix pomatia the supporting cells are somewhat smaller and the apical differentiation consists of candelabra-like protrusions, which are usually three times dichotomously branched. The final branchings, corresponding to microvilli, are called terminal twigs. They are covered by a surface coat, which forms a feltwork. The cytofilia and cilia of the sensory cells that intertwine among the protrusions are confined to the space below the terminal twigs, where they compose the spongy layer.
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  • 123
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    Journal of Morphology 168 (1981), S. 151-157 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The intraglandular distribution of adrenergic and cholinergic nerve fibers was studied histochemically in the parotid, mandibular, and sublingual glands of six species of edentates belonging to the three families that comprise the order; namely, the Dasypodidae (armadillos), the Myrmecophagidae (anteaters), and the Bradipodidae (sloths). The following histochemical techniques were used: (a) acetylcholinesterase reaction for the demonstration of cholinergic fibers; (b) formaldehyde- and glyoxylic acid-induced fluorescence for the demonstration of adrenergic fibers. In addition, norepinephrine (NE) was assayed fluorimetrically in the mandibular and parotid glands of the armadillo. A network of acetylcholinesterase-positive nerve fibers surrounds the intra- and interlobular ducts and endpieces of all glands; it is of low density in the mandibular and sublingual gland of the sloth, of high density in the sublingual gland of the anteater and of moderate density in the remaining glands. A vascular cholinergic innervation occurs in all salivary glands. Although present around the vessels, adrenergic new fibers were virtually absent from the parenchyma of all glands, even after in vitro incubation of glandular tissue with NE, or after administration of NE to armadillos previously treated with a monoamine oxidase (MAO) inhibitor. Consistent with this fact, the amount of NE present in the parotid and mandibular gland of the armadillo was extremely low. These findings may indicate that the salivary secretion in the edentates is regulated by the parasympathetic rather than by the sympathetic nervous system.
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  • 124
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    Journal of Morphology 168 (1981), S. 73-84 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Morphology and functional aspects of the scotopic compound eye of the moth Diatraea saccharalis, studied using light and electron microscopy, is presented. An ommatidium is composed of a laminate corneal lens, four Semper cells, a refractive cone, two primary pigment cells, six screening pigment cells, a crystalline tract that functions as an optical waveguide, and six to eight sensory retinular cells. Accessory light regulators consist of screening pigment cells that, in the dark-adapted position, increase receptor sensitivity by permitting light rays to cross over to adjacent ommatidia and specialized tracheal regions that enhance sensitivity by reflecting light back toward sensory receptors.
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  • 125
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    Notes: Cells of the avian epidermis (rictus of the chicken), when examined under the light microscope following suitable fat staining, show similarities to epithelial cells of the uropygial gland of chicken and pigeon, an organ which is recognized both morphologically and functionally as a holocrine gland. Evidence thus far from electron microscopic studies strongly suggests that the skin of the bird is also a holocrine gland, although details of cytogenesis and secretion differ somewhat in the two organs.
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  • 126
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    Journal of Morphology 169 (1981) 
    ISSN: 0362-2525
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  • 127
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    Journal of Morphology 169 (1981), S. 185-190 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Seventy-nine chick embryos were examined by light microscopy and scanning electron microscopy to determine the mechanism of primary palatal development. Fusion between two discrete processes, the medial nasal and maxillary prominences, was found to be necessary for formation of a complete primary palate. This was one component of a three-stage process that included: (1) invagination of the nasal pit prior to the appearance of the facial prominences; (2) fusion between the medial nasal and inaxillary processes caudal to the nasal groove; (3) rupture of the bucconasal membrane. The lateral nasal and maxillary prominences were found to be part of the same tissue mass. Mergence was proposed as a mechanism for the obliteration of the groove between these two localized prominences. These results were compared with those obtained by other authors for primary palate formation in rodents and man.
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  • 128
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    Journal of Morphology 168 (1981), S. 51-71 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The topography and histology of the skin of the naked mole (Heterocephalus glaber) have been correlated with its behavior. The integument is exceptionally loose, thereby reducing integumentary stresses when the animal is digging and moving in narrow tunnels. It also allows the position of the nasolabial sensory patch to change. This patch is exposed to mechanical stimuli when Heterocephalus moves along the tunnel, but becomes partially shielded by a transient buccal evagination, the formation and function of which are here described. Most of the differentiated patches of the skin lie in the cranial and anogenital regions. The eyes are microphthalmic and nearly completely closed by the nonmobile eyelids; there is no pinna, hair-coat or sweat glands.The epidermis is of variable thickness; in some places it has only one layer of cells. The detached epidermal cells penetrate the dermis irregularly.The epidermis of Heterocephalus is specialized by modifications of its germinative stratum, equivalent to an epidermosis, the syndrome of which consists of reduction of all types of epidermal buddings - pilogenetic and adenogenetic - as well as those which have a mechanical significance.
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  • 129
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    Journal of Morphology 168 (1981), S. 85-96 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Fifteen minke whale (Balaenoptera acutorostrata: Mysticeti) and three bottlenose whale (Hyperoodon ampullatus: Odontoceti) hearts were obtained from Norway. Only the ventricular mass and the base of the great arteries were available for study. The shape of the heart, the double apex, the narrowness of the interventricular septum in the dorsiventral plane, the side-to-side position of the ventricles, the relative thickness of the wall of the right ventricle, and the heavy trabeculation agree with other, brief reports of whale heart morphology. Coronary artery tortuosity, which has been described in sperm whales by others, was found in the bottlenose but not in the minke whales. It is suggested that the shape of the heart is associated with depth and duration of dives and that the pattern of trabeculation may be related to the size of the animal.
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  • 130
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    Journal of Morphology 168 (1981), S. 109-119 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In this study, the innervation of cerebrally related retial arteries in the narwhal Monodon monoceros was examined. Vessels were processed for the demonstration of adrenergic nerve endings by fluorescence histochemistry, and the results were confirmed by electron microscopy. Innervation of cerebrally related retial arteries was compared to that of a system situated in the haemal canal and supplying the tail. The retial arteries were poorly innervated. Adrenergic nerve endings, as indicated by fluorescence, occurred only in caudal portions of the spinal rete. Ultrastructurally, nerves were found in most retial vessels examined. However, except for arteries from caudal portions of the spinal rete, nerve numbers were few and because they occurred in outer layers of the adventitia were probably not functionally significant. In contrast, vessels in the haemal canal were well innervated. Nerve endings possessing neurotransmitter vesicles were adjacent to the smooth muscle cells. The cetacean rete mirabile, a system which supplies blood to the entire central nervous system, is apparently not under extensive nervous control, even though most reports suggest there is a relationship, possibly based on the presence of adjacent nerve trunks. Any vasomotor activity that does occur, possibly does so in response to catecholamines or other vasoactive agents circulating in the blood.
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  • 131
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    Journal of Morphology 168 (1981), S. 159-170 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The ultrastructure of wax glands (integumentary, stigmatic, and peristigmatic glands) was investigated in larvae, cysts, and adult females and males of species belonging to the genera Porphyrophora, Sphaeraspis, and Eurhizococcus. The general organization and cytological characteristics are similar for all glands studied. Each gland is composed of a single layer of 8 to 40 cells. The glandular cells are characterized by a very large quantity of smooth endoplasmic reticulum which forms dense zones throughout the cytoplasm, but is always placed near the collecting canals in the presence of mitochondria. Each cell has a central canal reservoir which penetrates it deeply and gives rise to a large number of lateral collecting canals, formed by the invagination of the apical plasma membrane. The canals open into a subcuticular cavity forming a common reservoir in which the secretion is accumulated. This reservoir is covered by a modified cuticle formed from the endocuticle and the epicuticle. The endocuticle is composed of a network of fine tubular structures and has many filaments on its surface. The epicuticle is perforated by numerous pores. There is no cuticular duct. The secretion crosses the cuticle in three successive steps. First, it passes through the filaments, then through fine tubular structures of the endocuticle, and finally through the epicuticular pores.
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  • 132
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    Journal of Morphology 168 (1981), S. 171-179 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Many aspects of the developmental stages of the oocyte of the dog resemble those of other mammalian species. The oocyte of the dog, however, contains large amounts of lipid yolk material. A study of the ultrastructural morphology of early growth and maturation of dog oocytes was undertaken to clarify the nature and appearance of this yolk material. The lipid yolk first appears in early primary oocytes as aggregated dense bodies that gradually fill the ooplasm as the oocyte matures. The site of the yolk's initial appearance is consistently related to a single centriole and often to the lamellae of smooth endoplasmic reticulum that surrounds groups of forming lipid yolk bodies. Dense cortical granule-like vesicles are found to lie deep within the maturing oocyte and often are enclosed within the lamellar yolk space. Granules within this space undergo changes in size, matrix configuration, and vacuolization. These changes suggest a mechanism whereby material is added to the lipid yolk bodies. Light microscope histochemistry for lipid and polysaccharide material is described.
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  • 133
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    Notes: The various sensilla on the antennae and on the labial and maxillary palps of Blattella germanica (L.) were studied. Thick-walled chemoreceptors with fluted shafts and articulated bases are located on the antennae and on the labial and maxillary palps. Thin-walled chemoreceptors, without fluted shafts or articulated bases, are restricted to the flagellar segments of the antennae and to the distal segments of the palps. Antennae of adult males have more thin-walled chemoreceptors than do those of females. Hair-plate sensilla are found at the scape-head and scape-pedicel joints, and at the joints of segments on the palps. Campaniform sensilla are concentrated as a ring around the distal margin of the pedicel, and are also scattered singly on the scape, pedicel, and flagellar segments of the antennae, and on the first segment of the maxillary palps. Occasionally, a few sensilla coeloconica and cold receptor sensilla are found on the antennal flagellum.
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  • 134
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    Journal of Morphology 168 (1981), S. 321-329 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The numbers, types, and distributions of neurons in a hypostome of Hydra littoralis were determined from electron micrographs of serial (0.25 μm thick) sections. In 1,080 serial sections examined we found 75 sensory cells and 949 centrally located ganglion cells. More than 96% of the 1,024 neurons identified had a single cilium.Sensory cells were most numerous near the apex of the hypostome. Proceeding away from the apex, they steadily decreased in numbers; at 120 μm they were no longer observed. Ganglion cells were bimodally distributed; some were associated with sensory cells at the apex, but most were found at the sites of tentacle origin.We observed, throughout the hypostome, a total of 64 neuronal clusters (three or more contiguous neurons), with an average of five and a maximum of 11 neurons in a cluster. Clusters were distributed similarly to ganglion cells: an initial concentration of clusters near the apex; the majority at the hypostometentacle junctions.Each neuron identified was traced through succeeding sections in which it was observed. We used a three coordinate system to create a three-dimensional reconstruction of the neuronal locations in the hypostome. Although the functional significance of the neuronal distributions we observed is unknown, we suggest that neurons at the apex of the hypostome transduce sensory information involved in feeding behavior. The neuronal concentrations at sites of tentacle origin may be responsible for initiating Contraction Burst Pulses associated with rhythmic behavioral patterns of Hydra or coordinating tentacle movements involved in prey capture, ingestion or locomotion.
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  • 135
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    Journal of Morphology 170 (1981), S. 55-69 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The spinotectal somatosensory projection was compared in normal, genetically eyeless, and embryonically manipulated salamanders. In normal animals, serotonin fluorescence was restricted to the intermediate tectalneuropil. This same region showed both high levels of serotonin uptake and somatosensory single unit electrical activity. In mutant eyeless salamanders and in normal animals enucleated early in development, serotonin fluorescence, serotonin uptake, and somatosensory activity were present in the superficial tectal neuropil. One-eyed animals, either genetically normal axolotls with one eye enucleated embryonically or genetically eyeless animals in which a normal eye had been transplanted, showed normal intermediate serotonin fluroescence and somatosensory physiology in the visually innervated half-tectum. In the visually uninnervated half-tectum, they showed superficial serotonin fluorescence and somatosensory physiology.In normal animals, 5,7-dihydroxytryptamine (5,7-DHT), a specific poison for serotonergic fibers, eliminated physiological responses in the contralateral somatosensory tectal region. The 5,7-DHT poisoning also abolished U.V.-induced serotonin fluorescence in the intermediate tectal neuropil.These results are discussed in terms of (1) evidence for serotonin as a central neurotransmitter for somatosensory information in the tectum, (2) the effects of eyelessness on tectal organization, and (3) related results in other animals.
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  • 136
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    Notes: Vascular architecture and the structure of the intestinal hematopoietic centers of two cyclostomes, the hagfish Eptatretus burgeri and the ammocoetes larva of Entosphenus reissneri, are compared. Blood cells of the hagfish are generated in hematopoietic nests that develop around intestinal veins established primarily for transport of absorbed nutrients. In ammocoetes, on the other hand, blood cells are generated in hematopoietic nests of the typhlosole, closely associated with venous sinusoids developing around the longitudinally oriented mesenteric artery of the typhlosole. A collateral vein of the mesenteric artery is completed in the typhlosole after metamorphosis. Since the spleen of higher vertebrates develops in relation to establishment of the collateral vein of the largest foregut artery, the intestinal hematopoietic nests of ammocoetes may be regarded as a model of the primitive form of the spleen of higher vertebrates. Hematopoiesis in the hagfish intestine is not related to establishment of a collateral vein; hence „primitive spleen“ or „intestinal spleen“ may be improper terms in reference to the intestinal hematopoietic tissue of the hagfish.Morphological characteristics of the hematopoietic nests of the two cyclostomes are essentially the same. Blood cells of these nests are generated in the intervenous tissue, supported by interstitial connective tissue cells and reticulin fibers. Granulated cells are the most common type in the primitive hematopoietic nests. No definitive erythrothrombocytopoiesis has been identified. Lymphocytes have not been observed in the hagfish; however, small lymphocytes have been observed in the vascular lumen of sinusoids around the hematopoietic nests of ammocoetes. These lymphocytes probably originate outside of the typhlosole.
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  • 137
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    Journal of Morphology 170 (1981), S. 207-214 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In this paper we describe the gross and microscopic anatomy of the internal carotid artery and demonstrate that this vessel does not directly supply blood to the brain, in the Monodontidae (order Cetacea). Our account is based on gross dissections and perfusion casts of the arterial vasculature in Delphinapterus leucas and Monodon monoceros and on histological material from the latter species.The internal carotid artery originates low in the neck and extends to the carotid rete at the base of the brain. The vessel tapers dramatically along its cervical course and changes from an artery elastic in nature to one more muscular. A single large cervical branch occurs in D. leucas and supplies cerebrally related retia in this region and prevertebral muscles. No cervical branches occur in M. monoceros. In otic regions, the internal carotid artery is small and muscular. A lumen is present; however, a split internal and external elastic lamella and a thickened subendothelial layer are evident. Though patent in the neck and ear, the vessel appears occluded within the carotid canal. At this level, the vessel is characterized by absence of a lumen and by fragmented elastic lamellae.We conclude that the internal carotid artery is anatomically closed at a level just proximal to the carotid rete and hence has no direct involvement with cerebral blood supply in the Monodontidae. Our results confirm other investigators' work on smaller cetacean species.
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  • 138
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    Journal of Morphology 170 (1981), S. 321-345 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Fiber type composition distinguished by the level of succinic dehydrogenase, mean fiber diameter, and fiber number were determined for the gracilis major and sartorius in ontogenetic series of the anurans Rana pipiens, Bufo americanus, and Xenopus laevis to characterize muscle composition and mode of muscle growth.A correlation can be made between the respective locomotor mode of these anurans, their activity physiology, and the fiber type composition of the propulsive muscles. R. pipiens and X. laevis have hindlimb muscles composed primarily of fast-twitch, fast-fatiguing type 1 fibers. B. americanus's muscles are composed of slow-twitch, slow-fatiguing type 2 and type 3 fibers. Fiber typing is apparently useful in explaining interspecific anuran locomotor capability previously difficult to correlate with body shape. Fiber typing also affords an explantion for reported variations in metabolism during strenuous activity.Postmetamorphically, anuran muscles grow by a combination of hyperplasia and hypertrophy, but the percent fiber type composition remains unchanged. In R. pipiens and X. laevis, the muscles grow primarily by hypertrophy with the addition of relatively fewer fibers. The converse is true for B. americanus. In all three species the combinations result in strong positive allometric increases in muscle cross section. Anuran muscle growth is similar to that reported for fish and different from that associated with mammals.
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  • 139
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    Notes: The density of intramembranous protein particles was studied by freeze-fracture. Particle density on the fracture faces of the plasmalemma and the rough endoplasmic reticulum (RER), as well as the outer and inner membranes of the nucleus and the mitochondria in rat hepatocytes were quantified. Comparison among different age groups sampled days postcoitum (dpc), days postpartum (dpp), and months postpartum (mpp) shows age-related changes in particle density in each membrane system. With the exception of the RER, particle densities increased after the 16th dpc, reached a maximum at birth, and then decreased with increasing age. Simultaneously, the number nuclear pores shows a positive correlation with the particle density of the nuclear membranes. The particle density on the membranes of the RER shows a maximum on the 16th dpc, and on the 6th dpp. Thereafter, the density of the RER decreases slightly. In all membrane systems, the density of the particles on the external fracture faces is more variable than the density of the particles on the protoplasmic fracture faces.
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  • 140
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    Notes: The muscular system in the posterior sucker of Branchiobdella pentodonta Whit. has circular, longitudinal and radial fibers. In the anterior sucker, which has circular and longitudinal fibers, the muscle system is scarce. Concentric fibers are found around the mouth. In both suckers the glandular elements form voluminous complexes secreting mucus for attachment to the substrate. Suckers show neuromuscular junctions and three distinct types of neuroglandular junctions: one with typical neurosecretory granules, one with larger neurosecretory granules produced by cells located at the origin of the segmental nerves, and one with presynaptic vesicles. The second type is peculiar to the posterior sucker. A comparison is made between suckers of Branchiobdella and those of leeches.
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  • 141
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    Journal of Morphology 170 (1981), S. 273-282 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Arboreal salamanders of the Neotropical genus Bolitoglossa are characterized by palmate, fully webbed feet. The feet act as adhesive structures enabling the salamanders to cling to smooth surfaces. Scanning electron microscopy of skin epithelium and light microscopy of serial sections show exceptionally smooth cell surfaces and increased numbers of mucous glands on the soles of the feet. These features enhance the abilities of the feet to adhere by means of surface tension and suction. They are part of a set of morphological characteristics that may have been produced as a result of paedomorphosis.
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  • 142
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    Notes: The eyestalk of Astacus leptodactylus is investigated immunocytochemically by light, fluorescence, and electron microscopy, using an antiserum raised against purified crustacean hyperglycemic hormone (CHH). CHH can be visualized in a group of neurosecretory perikarya on the medualla terminalis (medulla terminalis ganglionic X-organ: MTGX), in fibers forming part of the MTGX-sinus gland tractus, and in a considerable part of the axon terminals composing the sinus gland. Immunocytochemical combined with ultrastructural investigations led to the identification of the CHH-producing cells and the CHH-containing neurosecretory granule type.
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  • 143
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    Journal of Morphology 169 (1981), S. 21-28 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Standard histological and SEM techniques have been used to examine the pair of statocyst organs located in the telson of the isopod, Cyathara polita. Each organ is formed as an invagination of the dorsal cuticle of the telson. The invagination narrows to form a stalk between the statocyst and dorsal surface. A canal courses longitudinally through this stalk and forms a continuous channel between the lumen of the cyst and the external environment. On the luminal floor of each statocyst, there are three pits; each correlates with a nodule protruding from the ventro-medial wall. From each pit, a single, bifurcating hair projects dorsally to contact the single concretion within the statocyst lumen. No other static organs have been found in this animal. Thus, maintenance of equilibrium in this species appears to be under the control of but six hairs, three in each statocyst. Innervation of each statocyst is provided by a branch of a nerve which connects anteriorly with the last abdominal ganglion.
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    Journal of Morphology 179 (1984) 
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    Journal of Morphology 179 (1984), S. 119-134 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The ultrastructure of cellular organelles involved in stylet formation is examined in six species of nemertean worms by transmission electron microscopy (TEM). Stylets are nail-shaped structures containing calcium phosphate that are assembled intracellularly in large uninucleate cells, called styletocytes. Each stylet develops within a membrane-bound vacuole in the styletocyte cytoplasm. Well developed arrays of Golgi bodies are typically found in the vicinity of developing stylet vacuoles, and fully formed vacuoles are filled with PAS+ material that appears to be derived from the smooth endoplasmic reticulum. At the onset of styletogenesis, a conical sliver of organic material differentiates on the inner surface of the vacuolar membrane. This material displays a species-specific banding pattern in decalcified sections, and apparently acts as a template during calcification of the stylet shaft. After the organic core of the shaft is formed, mitochondria aggregate around the stylet vacuole and presumably help accumulate the calcium used in mineralization of the stylet. A knob-shaped proximal piece is subsequently assembled on the base of the shaft. The proximal piece contains a nonbanded matrix and has electron-dense material at its surface that may help in correctly orienting this region toward the basis during replacement of the central stylet.
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  • 146
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    Journal of Morphology 179 (1984) 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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  • 147
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    Journal of Morphology 179 (1984), S. 203-228 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Integumentary development on the dorsal and ventral aspects of the body of 14, 21, 26, 33, and 40-day incubated embryos of the European Wall Lizard (Lacerta muralis) is described. While the earliest stages of epidermal differentiation resemble those reported for other tetrapods, precocious differentiation of dermal collagen more resembles that of anamniotes than that of birds and mammals. Anchoring complexes comprising cellular components, anchor filaments, and collagen are described, and their possible relationship to the formation of scale anlagen is discussed. The first embryonic epidermal generation differentiates beneath the periderm; most features of its histogenesis resemble those that have been described for the epidermis of adult squamates, but certain previously ignored organelles, including possible earlier β-keratin precursors, are reported. Different strategies regarding in ovo peridermal loss and posthatching shedding behavior are described and discussed in light of presently available data concerning control of cell differentiation in the squamate epidermis.
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  • 148
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    Journal of Morphology 179 (1984), S. 243-262 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The fine structure of the male reproductive system of the hermaphroditic brittle-star, Amphipholis squamata, has been studied in specimens from both the Pacific coast (Washington) and the Atlantic coast (New Hampshire). Each testis is a small (100-μm) sphere and is attached to the internal wall of the bursa by peritoneal suspensor cells. Occasional flagellated cells are found on the external surface of the testis. The testicular wall of A. squamata is a multilayered structure, similar to that of other ophiuroids, but the hemal sinus is PAS negative in this species. Germinal cells are surrounded throughout their development by the filopodia of interstitial cells. Adjacent interstitial cells are interconnected, and thus form a structural network within the testis. Positionally and functionally, the interstitial cells resemble Sertoli cells; however, their origin, behavior and ultrastructure are different in many ways.Spermatogenesis includes a series of cyclical changes (aspermatogenic phase, proliferative phase, differentiative phase, and evacuative phase). Within a single testis, the resulting production of sperm is in short pulses, but if all 10 testes are taken together, sperm are produced continuously throughout the year. The events of spermiogenesis closely follow those that have been described in other echinoderms. However, we have provided new information on the release of excess cell membranes and the fusion process of mitochondria.The mature spermatozoa of A. squamata are flagellated and motile, and have “primitive” structural features, in spite of the fact that they fertilize the eggs inside the genital bursae. The spermatozoa do not, as was previously thought, enter the bursa by rupture of the adjacent walls. Instead, they are ejaculated through a gonoduct into the rapid incurrent flow of water entering the bursa. The locomotion of the spermatozoa is in eccentric spirals, due to the unusually large angle at which the flagellum is inserted into the base of the sperm.
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  • 149
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    Journal of Morphology 180 (1984), S. 1-2 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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  • 150
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    Journal of Morphology 180 (1984), S. 3-17 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The choanoderm and pinacoderm of representatives of the two families of Homoscleromorpha sponges, the Oscarellidae and Plakinidae, have been examined by transmission and scanning electron microscopy. Different fixative procedures have shown the dramatic influence of fixation conditions on the morphology of choanocytes. These two families of sponges have the following morphological features in common: flagellated endopinacocytes with short apical microvilli and basal pseudopods; the presence of a very thin and dense sheet of matrix material which limits the mesohyl. There are, however, only minor differences in the flagellar morphology, granule content, and anchoring system of their choanocytes.Two findings are of particular interest: (1) the presence of glycocalyx bridges between the microvilli of the choanocyte collar; and (2) the discovery of a new cell type, the apopylar cell, which has a morphology intermediate between that of pinacocytes and choanocytes. The apopylar cells limit the apopylar opening of the choanocyte chamber and indicate the transition between choanoderm and pinacoderm.
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  • 151
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    Journal of Morphology 179 (1984), S. 47-58 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The formation of the micropylar apparatus during oogenesis in the silkworm, Bombyx mori, has been studied using light and transmission electron microscopy. The micropylar apparatus is formed by three types of cells: the micropylar channel-forming cells (MCFCs), the micropylar orifice-forming cells (MOFCs), and the micropylar rosette-forming cells (MRFCs). During the formation of the vitelline membrane and the chorion, each of the MCFCs extends a cytoplasmic projection serving as the mold of a micropylar-channel into the egg envelopes. The detachment and collapse of the projections takes place at the end of choriogenesis. The micropylar channels possess a common external orifice on the chorion and several internal orifices within the vitelline membrane. The MOFCs interact closely with the MCFCs and contribute to the formation of the external micropylar orifice. A petal-like rosette surrounding the orifice is imprinted on the outer chorionic surface by the MRFCs which enclose a group of the MCFCs and MOFCs.
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  • 152
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    Journal of Morphology 179 (1984), S. 95-114 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Quantitative lateral and dorsoventral cineradiography shows that the masticatory movements of the mandible, condyles, tongue, and hyoid of Pteropus giganteus (Chiroptera) move along highly regular paths that are characteristic for each of the three food types tested.Mandibular movements are predominantly orthal, although a small forward translation occurs early in opening and small lateral deflections occur in both opening and closing phases. These deflections are related to the existence of active (bolus bearing) and balancing sides of the jaws, chewing being not truly bilateral. The deflections are associated with a shift of both condyles toward one side. In consequence the active condyle is located in a lateral part of the associated fossa, the inactive condyle in a medial part. Food transfer from side to side involves a reversal of the chewing direction during opening. Such reversals are especially frequent near the end of a chewing sequence.The fore, middle, and hind parts of the tongue differ in their movement patterns. Movements of the fore part, and to a lesser extent of the middle part, follow the open-close movements of the lower jaw. The hind part of the tongue moves predominantly dorsally during slow closing and ventrally during fast opening and fast closing. All three parts move forward during slow closing and slow opening, and backward during fast opening and fast closing. Movements of the hyoid are closely synchronized with those of the hind part of the tongue. Furthermore, tongue and hyoid movements are synchronized with jaw movements. All cycles of Pteropus giganteus are transport cycles, and the synchrony appears to reflect the consistency of the food (soft pulp, juices). Food consistency also accounts for the high swallowing rate and the absence of any significant difference between nonswallowing and swallowing cycles.
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  • 153
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    Journal of Morphology 179 (1984), S. 153-174 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: The anterior dorsal ventricular ridge was examined in the American alligator, Alligator mississippiensis, with cresyl violet and Golgi-Kopsch preparations. Four cytoarchitectonic areas (lateral dorsolateral, medial dorsolateral, intermediolateral, and lateral) can be distinguished by variations in the density of neurons and their tendency to form clusters of neurons with apposed somata. Three distinct types of neurons are distributed throughout these areas. Juxtaependymal neurons lie near the ventricular surface and have dendritic fields paralleling the ependymal layer. Their dendrites bear a moderate density of spines. Spiny neurons all have stellate shaped dendritic fields and dendrites that bear dendritic spines, but they vary greatly in the density of spines and the thickness of their dendrites. A very spiny variety has a high spine density and relatively thick dendrites. A moderately spiny variety has a moderate spine density and thin dendrites. A sparsely spiny variety has a low spine density and thick dendrites. Aspiny neurons have a relatively large number of dendrites that form a gnarled dendritic field and lack spines.
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  • 154
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    Journal of Morphology 179 (1984), S. 175-195 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Notes: A histological investigation of the filtering function of the spleen of the sunfish Lepomis spp. was conducted by light, scanning, and transmission electron microscopy. The parenchyma of the organ is predominantly red pulp, a system of splenic cords and sinuses. The white pulp consists of loose lymphoid tissue which forms a cuff around the pulp arteries. Filtering of particulate matter from the blood occurs in the red pulp by phagocytes of the pulp cords and ellipsoids (periarterial macrophage sheaths). The ellipsoids are pale-staining cuffs of macrophages and reticular cells in a framework of reticular fibres surrounding the arterial capillaries. Destruction of effete blood cells (especially erythrocytes) is confined to the pigment nodules; particulate matter is not taken up by the nodules. These yellow-brown bodies are dispersed throughout the red pulp and are bounded by a reticular capsule. They contain masses of phagocytes and have the appearance of a morula. They are associated with blood vessels and are surrounded by sinusoids. Prussian Blue stain shows the presence of haemosiderin within their phagocytes. The phagocytes of the pigment nodules are filled with inclusions such as residual bodies, siderosomes, and fragments of erythrocytes. The early filtering of particulate matter by the phagocytes of the pulp cords and ellipsoids may allow for a more efficient phagocytosis of erythrocytes by the pigment nodules, followed by storage and reutilization of iron-containing compounds uncontaminated by other phagocytosed material.
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  • 155
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    Journal of Morphology 170 (1981), S. 215-237 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: Hermaphroditism and sex reversal have not previously been ruled out adequately as possible explanations for the existence of unisexual species of reptiles. Therefore, we examined serial histological sections of the complete urogenital systems of nine F2 specimens belonging to two ontogenetic series of Cnemidophorus exsanguis raised in captivity in isolation from males, as well as the urogenital system of the F1 mother of one of these series. No evidence of spermatozoa or testicular tissue was found in any specimen. Comparative material reveals that the histology of the urogenital tract, including the mesonephric kidney in adults, is similar to that of females of bisexual species of Cnemidophorus. We conclude that C. exsanguis is a unisexual, parthenogenetic species whose normal reproduction does not involve sex reversal, self-fertilization, gynogenesis, hybridogenesis, or spermatozoa in any way whatsoever.
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  • 156
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    Journal of Morphology 180 (1984), S. 81-103 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Topics: Biology , Medicine
    Notes: The distribution of the ganglia and nerves of the stomatogastric nervous system and the innervation of the extrinsic and intrinsic muscles are described. Median unpaired frontal and hypocerebral ganglia and paired ingluvial ganglia are present. The anterior pharynx is innervated by branches of the frontal nerve and by the anterior and posterior pharyngeal nerves, originating from the frontal ganglion. The posterior pharyngeal nerves are linked to nerves innervating the posterior part of the pharynx which have their origin in the hypocerebral ganglion, the anterior portion of which has previously been regarded as part of the recurrent nerve. Paired esophageal nerves run the length of the esophagus and crop between the hypocerebral and and ingluvial ganglia, innervating the muscularis by serial side branches. From each ingluvial ganglion runs an ingluvial nerve which innervates the gizzard and a cecal nerve which innervates the midgut and its ceca. At the posterior end of the midgut there is a poorly developed nerve ring. Nerves running posteriorly from this nerve ring link the stomatogastric nervous system with the proctodeal innervation from the terminal abdominal ganglion.Multipolar peripheral neurons are present on the muscularis of the whole of the foregut, rather randomly distributed on the crop and gizzard but forming fairly definite groupings at some points on the pharynx. Though of varied appearance, these cells could not be divided into discrete morphological categories. Peripheral neurons on the midgut are of different and characteristic morphology, though a few cells of the same appearance as those of the foregut occur at the midgut-hindgut boundary. Nerve fibers on the gut almost invariably terminate on the fibers of the muscularis.
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  • 157
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    Journal of Morphology 180 (1984), S. 171-171 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Topics: Biology , Medicine
    Notes: No Abstracts.
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  • 158
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    Journal of Morphology 180 (1984), S. 213-221 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The bursa compulatrix of the Monarch butterfly was investigated utilizing light microscopy, histochemistry, and scanning and transmission electron microscopy in order to relate its morphology to the release of sperm from the spermatophore. The bursa has a row of large chitinous teeth on either side of the organ. The dorsal and ventral surfaces are covered with chitinous plates, the plates having bristles on one side. A single layer of cells lies under both the plates and teeth, one columnar cell under each plate, one cuboidal cell under each tooth. The toothed area has no muscle cells. However, the dorsal and ventral hemispheres of the bursa each have a crescent-shaped packet of muscle fibers that traverse the organ; there are no longitudinal fibers. Spermatophores with thick walls were found in the bursal lumen. Morphological evidence suggests that the presence of the spermatophores is sensed by the bristles and that the packets are opened by contraction of the muscles bringing the large teeth into contact with the spermatophore wall.
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  • 159
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    Journal of Morphology 180 (1984), S. 223-242 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The skink, Mabuya multifasciata, torus semicircularis was subdivided into the central (CN), the laminar (LN), and the superficial (SN) nuclei using Golgi and Nissl methods. The central nucleus consisted of small ovoid neurons surrounding a core of fewer large ovoid-triangular and fusiform neurons. The ovoid cells had scant cytoplasm and two to five dendritic trunks. Most of these processes were directed around the periphery of the central nucleus. The large neurons had clumped, darkly staining Nissl substance and a central nucleus. The sparse dendritic spine population on these cells increased distally on the three to five radiate dendrites. The laminar nucleus was present caudal and ventral to the central nucleus. At more rostral levels it was medial and dorsomedial to the central nucleus. The NL had three to five layers of ovoid and fusiform neurons. Scattered within these layers were a few ovoid-triangular neurons. Ovoid neurons had eccentric or central nuclei. The arborization of their dendrites was generally medial and lateral but was frequently oriented caudomedial and rostrolateral. Fusiform neurons had pale Nissl substance, central nuclei, and one to two dendritic processes. The ovoid-triangular neurons had dense, clumped Nissl substance and at least two dendritic trunks with few spines. The superficial nucleus was dorsal, lateral, and caudal to the central nucleus. Extending ventrolaterally around the central nucleus, the superficial nucleus became confluent with the laminar nucleus, ensheathing the central nucleus ventrally, laterally, and dorsally. Rostrally the central nucleus was covered by the layers of the laminar nucleus. Within the superficial nucleus were ovoid, fusiform and sparse ovoid-triangular neurons. The study indicated that the morphology of the torus semicircularis in the golden skink was similar to that in other lizards. This similarity correlates with the degree of development as it relates to the auditory function, but was independent of the type of inner ear restraint mechanism.
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    Journal of Morphology 181 (1984), S. 239-270 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The mastoid auditory bulla of the extinct marsupial sabertooth, Thylacosmilus, has an enlarged, complex hypotympanic sinus but lacks an alisphenoid contribution. These are marked departures from the usual marsupial condition. Details of the ear region of Thylacosmilus are compared with those of the convergent, extinct placental sabertooth, Smilodon, and each is compared with less specialized related forms to define differences and similarities of the evolutionary paths that led to the striking overall convergence.Functional factors such as pressure transformer ratio (PTR), impedance transformer ratio (ITR), acoustic impedence at the eardrum, and the fraction of the sound energy theoretically transmitted to the inner ear cannot be estimated for Thylacosmilus because certain critical measures are still unknown (tympanum size, ossicle lever arm ratios). However, in both sabertooths enlarged complex hypotympanic sinuses, characterized by expansions and contractions, are greatly developed. They vastly increase middle ear space (volume) and must have influenced these factors. In both, the sinuses provide the large air volume needed to prevent excessive damping of sound energy transmission (Hunt and Korth, '80), and both are believed to have achieved a further modulation of the system from the cushioning or “pillow” effect of the confined air as it directly damps the tympanum itself. Thylacosmilus has still another feature that may have given greater control over damping of sound energy transmission: the direct opening (probably membrane covered) of one of the sinus cavities into the side of the meatal tube. In this feature, as in others noted earlier (Turnbull, '76, '78), we see a greater degree of specialization in this marsupial sabertooth than in a placental counterpart.
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    Journal of Morphology 181 (1984), S. 319-331 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: The telencephalic medial wall of the lizard Psammodromus algirus was studied using Golgi and conventional light microscopic techniques. The area is formed by two different cytological fields - medial cortex and dorsomedial cortex. These two cortices possess three layers dorsoventrally: a superficial plexiform layer, a cellular layer, and a deep plexiform layer. The alveus, a deep fiber system, runs adjacent to the ependyma. Four classes of neurons are found in the cellular layer of the medial cortex on the basis of soma shape, dendritic pattern, and position in the layer: horizontal, double pyramidal, and candelabra cells. Solitary cells are present in the superficial and deep plexiform layers of the medial cortex. Those of the superficial plexiform layer are stellate cells. Horizontal and vertical cells are found in the deep plexiform layer. Double pyramidal cells are the most frequently impregnated in the cellular layer of the dorsomedial cortex. In addition, candelabra cells are present at the lateral end of the layer. Two cell types are found in the deep plexiform layer of the dorsomedial cortex: solitary pyramidal cells and, among the fibers of the alveus, horizontal cells. Ependymal tanycytes line the ventricular surface, and protoplasmic astrocytes are found in the plexiform layers of both medial and dorsomedial cortices.
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    Cell Motility and the Cytoskeleton 1 (1981) 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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  • 163
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    Cell Motility and the Cytoskeleton 1 (1981), S. 167-178 
    ISSN: 0886-1544
    Keywords: nerve growth ; actin ; tubulin ; antibodies ; immunofluorescence ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Embryonic chick nerve cells, from dissociated dorsal root ganglia, were cultured on polylysine substrata and examined for tubulin and actin distribution by indirect immunofluorescence.Antibodies generated against chick brain tubulin produced specific fluorescence in growth cones, neurites, and cell bodies without revealing distribution differences or substructure in the nerve cells. However, at reduced antitubulin concentrations, differences were resolved. Tubulin fluorescence remained uniform and intense in neurites and cell bodies, but exhibited reduced intensity and patterning in growth cones. Nonneuronal cells in the reduced intensity and patterning in growth cones. Nonneuronal cells in the cultures served as controls for typical cytoplasmic tubulin fluorescence distribution. Straining controls demonstrated that fluorescence resulted from tubulin-antitubulin binding.Analogous studies, using antibodies generated against chick brain actin, demonstrated distribution differences at reduced antiactin concentrations, including “hot spots” of intense fluorescence in growth cones and a paucity of fluorescence in neurites.
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    Cell Motility and the Cytoskeleton 4 (1984), S. 1-5 
    ISSN: 0886-1544
    Keywords: motility ; power output ; muscle ; flagella ; cytokinetic furrow ; mitotic spindle ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Cellular motile systems as diverse as muscle and the mitotic spindle have been compared by their specific power output: the maximum power they develop per unit of engine volume. Striated muscles and flagella have high specific output; their performance is comparable to that of typical automobile engines. The cytokinetic furrow and the mitotic spindle have very much lower specific power output. The furrow's output is 7,000 times lower than muscle and the spindle's is 300,000 times lower. Different macromolecules have been used to generate power in systems with similar output (muscles and flagella) and, conversely, the same macromolecular motor has been used in systems with very different output (muscles and cytokinetic furrows). The common feature amid this diversity is adaptation to a particular biological role, which specific power output reflects very well. High values are found where a powerful, compact engine should be advantageous, while low values are found where precision, not power, matters most.
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    Cell Motility and the Cytoskeleton 4 (1984), S. 76-76 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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  • 166
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    Cell Motility and the Cytoskeleton 1 (1981), S. 349-362 
    ISSN: 0886-1544
    Keywords: Ca2+ ; flagella ; symmetry ; vanadate ; spermatozoa ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Increased Ca2+ concentration causes a reversible increase in asymmetry of the flagellar bending waves of “potentially symmetric” demembranated sea urchin spermatozoa. When these flagella are immobilized with 5 μM vanadate, increased Ca2+ concentration causes a reversible increase in the total bend angle between the tip and the base of the immobilized flagella. These effects of Ca2+, and the movement which can be activated by CaATP2-, can be inhibited by vanadate, but in both cases, high concentrations of vanadate, of the order of 100 μM, are required. These observations suggest that ATP, possibly in the form of CaATP2-, is required for the Ca2+-induced change in shape of the flagella, but other observations suggest that the magnitudes of asymmetry and total bend angle are more closely related to Ca2+ concentration than to CaATP2- concentration.
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  • 167
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    Cell Motility and the Cytoskeleton 1 (1981), S. 363-370 
    ISSN: 0886-1544
    Keywords: Ca2+ ; Mg2+ ; symmetry ; flagella ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Potentially asymmetric spermatozoa are obtained when spermatozoa are demembranated in the presence of a low Ca2+/Mg2+ ion concentration ratio. They swim with asymmetric bending waves even when reactivated at low Ca2+ concentrations, and become more asymmetric when Ca2+ is increased. Potentially symmetric spermatozoa, which swim with symmetric bending waves at low Ca2+ and become asymmetric as the Ca2+ is increased, can be obtained by exposing the flagella to a high Ca2+/Mg2+ ratio, either during or subsequent to demembranation. The rate of this conversion is an increasing function of temperature and Triton concentration. Potentially symmetric spermatozoa can be reconverted to potential asymmetry, if the exposure to high Ca2+/Mg2+ is brief, and is terminated by addition of EGTA and Mg2+ before diluting the spermatozoa. The conversion to potential symmetry may involve removal of a labile component from the axoneme.
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    Cell Motility and the Cytoskeleton 1 (1981) 
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    Cell Motility and the Cytoskeleton 4 (1984), S. 29-40 
    ISSN: 0886-1544
    Keywords: microfilaments ; microtubules ; contraction ; collagen gel ; fibroblasts ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In vitro models have been developed recently to study the ability of fibroblasts to generate tensile force within collagen gels. The present study was initiated to assess the role of the cytoskeleton in the cell shape changes and force generation in one such model system. Porcine periodontal ligament fibroblasts (PPLF) were cultured within three-dimensional collagen gels attached to glass coverslips. Fluorescence microscopy, using nitrobenzooxadizole (NBD)-phallacidin labeling for microfilaments and tubulin antibody staining for microtubules, was combined with phase and Nomarski optics to determine the intra- and extracellular architecture of the cells and collagen fibers. Samples were observed from 30 minutes to 24 hours after initiation of cell attachment. During attachment and spreading, NBD-phallacidin staining changed dramatically until large microfilament bundles became prominent. Collagen fiber alignment, compaction, and finally tearing from the coverslip occurred during this time. After release of tension, microfilament bundles were no longer evident. The change in microtubule distribution during these processes was less dramatic, appearing to follow the change in cell shape. These results indicate that microfilaments play an essential role in generating force to align and compact collagen, while microtubules may have a secondary role only.
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    Cell Motility and the Cytoskeleton 4 (1984), S. 57-71 
    ISSN: 0886-1544
    Keywords: actin ; calcium ; coelomocytes ; ionophore ; pH ; shape transformation ; video microscopy ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We have investigated the ability of the Ca+ + ionophore A23187 to induce the transformation of petaloid sea urchin coleomocytes to the filopodial form. The response of individual cells to different media was observed with time-lapse phasecontrast video microscopy. In the presence of 1 mM CaCl2, isotonic medium containing 1-5 μM A23187 produces a similar shape transformation to that caused by hypotonic shock. Higher concentrations of ionophore (10-20 μM) induce the formation of filopodia that are thinner and less rigid than those generated by hypotonic shock or low doses of ionophore. A23187 also induces shape transformation in highly flattened cells that do not respond fully to hypotonic shock. The induction of cytoplasmic alkalinization by NH4Cl, methylamine-HCl, or the Na+ ionophore monensin does not induce shape transformation, suggesting that increased intracellular pH is not the stimulus for this process. Ultrastructural changes in cytoskeletal organization were examined in negatively stained detergent-extracted cells. Low doses of ionophore produce filopodia that are indistin-guishable from those of hypotonically shocked cells, with actin filament bundles that are straight and cohesive along their entire length. High concentrations of ionophore produce filopodia with filament bundles that branch repeatedly and splay apart near their tips, forming loops and irregular curves. These results suggest that an increase in intracellular free Ca+ + concentration acts as the trigger that stimulates coelomocyte shape transformation, but that abnormally high concentrations of intracellular Ca+ +, produced by high doses of ionophore, interfere with actin filament bundling.
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  • 171
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    Cell Motility and the Cytoskeleton 4 (1984), S. 387-401 
    ISSN: 0886-1544
    Keywords: bull sperm flagella ; motility ; time course ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Detailed measurements were made of the time course of the motion of bull spermatozoa. Fourier analysis of the data showed the time course to be basically sinusoidal within 2% to 3%. An asymmetry in the motion was present, resulting in a second harmonic component in the Fourier spectra of normal sperm of approximately 11% of the main component. When the energy metabolism of the sperm was inhibited or when the external viscosity of the medium was raised, the asymmetry was reduced. When the internal Mg2+ content of the sperm was lowered, the asymmetry was increased. The asymmetries and the corresponding second harmonic components in the Fourier spectra were correlated with the overall bend shape of the sperm and with the curvature of the path in which the sperm were swimming. Model calculations showed that the asymmetry could reside in either the internal active moments in the sperms or in the stiffness of the sperm fiagella.
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    Cell Motility and the Cytoskeleton 4 (1984), S. 417-430 
    ISSN: 0886-1544
    Keywords: flagella ; image analysis ; microcomputer ; motility ; parameter estimation ; Simplex method ; spermatozoa ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Parameters to describe flagellar bending patterns can be obtained by a microcomputer procedure that uses a set of parameters to synthesize model bending patterns, compares the model bending patterns with digitized and filtered data from flagellar photographs, and uses the Simplex method to vary the parameters until a solution with minimum root mean square differences between the model and the data is found. Parameters for Chlamydomonas bending patterns have been obtained from comparison of shear angle curves for the model and the data. To avoid the determination of the orientation of the basal end of the flagellum, which is required for calculation of shear angles, parameters for sperm flagella have been obtained by comparison of curves of curvature as a function of length for the model and for the data. A constant curvature model, modified from that originally used for Chlamydomonas flagella, has been used for obtaining parameters from sperm flagella, but the methods can be applied using other models for synthesizing the model bending patterns.
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  • 173
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    Cell Motility and the Cytoskeleton 1 (1981), S. 455-468 
    ISSN: 0886-1544
    Keywords: intercellular bridge ; intercellular communication ; cytokinesis ; squid ; ultrastructure ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Incomplete cytokinesis followed by the disappearance of the midbody and spindle remnant results in intercellular bridges between the cells of the blastoderm of the squid embryo. An electron microscope study of the morphology of the stages of development of the intercellular bridge is presented. Cytokinesis ceased as the furrow base reached a diameter slightly larger than the midbody. As furrowing stopped, a dense material accumulated to form a cylindrical sheath 50 nm thick, lining the inner surface of the furrow base. Proteolytic enzymes showed this material to have a significant protein component. As the midbody broke down, vesicles lined the inner surface of the bridge sheath. In this configuration, there was cyto-plasmic continuity between the cells, and organelles appeared to pass through the bridge.The intercellular bridge could become temporarily closed. Vesicles entered the channel and fused with the vesicles lining the inner surface of the sheath. The vesicles enlarged until the channel became occluded with a series of transverse cisternae, the edges of which were embedded in the material of the sheath. When the bridge reopened, the transverse cisterna appeared to dissociate from the sheath, move out of the channel, and break down. Occasionally bridges were seen in which the bridge wall appeared distorted into lobes. It is suggested that such bridges might be in the porcess of breaking down, resulting in the final separation of the cells.
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  • 174
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    Cell Motility and the Cytoskeleton 1 (1981), S. 499-515 
    ISSN: 0886-1544
    Keywords: dynein ; tubulin ; axonemes ; microtubules ; microtubule-associated proteins ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Microtubule-associated proteins (MAPs), isolated from brain tubulin, bound to and saturated outer fibers of Chlamydomonas flagella. MAPs present on these microtubules prevented the subsequent recombination of dynein. MAPs also bound to intact axonemes and thus did not specifically bind to the dynein binding sites on the A subfiber. A molar ratio of 1 mole MAP2 per 27 moles tubulin dimers at saturation of the outer fibers with MAP2 suggested that MAPs could effectively interfere with dynein recombination only if the MAPs were near the dynein binding sites to sterically prevent binding. However, electron microscopic observations indicated that MAPs were not localized but, instead, were dispersed around the outer fibers. In addition, MAP2 present at saturating amounts on in vitro assembled brain microtubules had no significant effect on dynein binding. Dynein-decorated microtubules contained clusters of arms suggesting that there may be cooperative interaction between the arms during dynein binding. Because the A subfiber of axonemes contains sites to which dynein preferentially attaches, MAPs may prevent recombination by interfering with cooperative binding to these specific sites. Dynein presumably binds with equal affinity to any protofilament on in vitro assembled microtubules, and, therefore, the MAPs may not be capable of effectively interfering with cooperative binding of dynein to these microtubules.
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    Cell Motility and the Cytoskeleton 1 (1981), S. 485-497 
    ISSN: 0886-1544
    Keywords: actin ; tubulin ; nucleotides ; polymerization ; microfilaments ; microtubules ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Both actin and tubulin, the major proteins of the cytoskeleton, bind nucleotide triphosphate (NTP) and exhibit the phenomenon of “polymerization-coupled” NTP hydrolysis. In this report I review the nature of polymerization-coupled NTP hydrolysis, and its possible role in the cellular function of actin and tubulin. Polymerization-coupled hydrolysis may be viewed as simply reflecting differences in the NTPase activity of free subunit as compared to polymer. Making assumptions concerning the values of various rate constants, it is possible to write expressions for the effects of NTP hydrolysis on the kinetics of polymerization. The role of NTP hydrolysis may be viewed in at least three different ways: (1) Hydrolysis alters the kinetics of assembly and disassembly. This leads to a consideration of the role of subunit flow in microtubule and microfilament function. (2) Hydrolysis is an essentially irreversible step that separates the assembly and disassembly reactions. This suggests a role of NTP in the regulation of polymer content during cellular cycles of assembly and disassembly. (3) NTP may allow transient stabilization of intersubunit bonds. This suggests a role of NTP in nucleation and possible regulation of nonequilibrium states of assembly.
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    Cell Motility and the Cytoskeleton 4 (1984), S. 7-23 
    ISSN: 0886-1544
    Keywords: axoplasm ; elastic modulus ; viscosity ; motility ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A magnetic sphere viscoelastometer has been developed to peform rheological experiments in living axoplasm of Loligo pealei. The technique includes the use of a calibrated magnetic sphere viscoelastometer on surgically implanted ferro-magnetic spheres in intact squid giant axons. The axoplasm was discerned to be “living” by the biological criterion of tubulovesicular organelle motility, which was observed before and after experimentation. From these in vivo experiments, new structural characteristics of the axoplasm have been identified. First, analysis of magnetic sphere trajectories has shown the axoplasm to be a complex viscoelastic fluid. Directional experimentation showed that this material is structurally anisotropic, with a greater elastic modulus in the direction parallel to the axon long axis. Second, both magnetic sphere and in vivo capillary experiments suggested that the axoplasm is tenaciously anchored to the axolemma. Third, it was found that axoplasm could be modelled as a linear viscoelastic material in the low shear rate range of 0.0001 to 0.004 s-1. The simplest mechanical model incorporating the discovered properties of the material in this range is Burger's model.
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    Cell Motility and the Cytoskeleton 4 (1984), S. 151-153 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Cell Motility and the Cytoskeleton 4 (1984), S. 227-229 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Cell Motility and the Cytoskeleton 4 (1984), S. 249-267 
    ISSN: 0886-1544
    Keywords: Paramecium ; trifluoperazine ; cilia ; calmodulin ; calcium ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Trifluoperazine (TFP), a drug that binds to Ca2+-calmodulin (CaM) complexes, altered swimming behavior not only in living paramecia, but also in reactivated, Triton-extracted “models” of the ciliate. By comparing the responses of living cells and models, we have ascertained that two sites of drug action exist in paramecium cilia. Swimming movements were recorded in darkfield stroboscopic flash photomicrographs; this permitted accurate quantitation of velocities and body-shape parameters. When living paramecia were incubated in a standard buffer containing 10 μM TFP, their speed of forward swimming fell over several minutes and their bodies shortened. Untreated paramecia backed up repeatedly and frequently upon transfer to a solution containing barium ions (the “barium dance”), but cells preincubated in TFP did not “dance.” Instead they swam forward slowly for long periods of time without reversing and occasionally then exhibited abnormally prolonged reversals. W7 effects on swimming mimicked low doses of TFP, and the analog W5 did not visibly alter normal swimming patterns. These results suggest that TFP induces a decrease in the intracellular pCa of living paramecia, perhaps by reducing the efficiency of a calmodulin-activated calcium pump in the cell membrane. Paramecia extracted with Triton X-100 and reactivated to swim forward (7 ≥ pCa ≥ 6) were not affected by addition of up to 40 μM TFP to the reactivation medium. We conclude that the main drug effect in living cells is probably not at the axoneme. However, at low pCa, TFP directly affected the ciliary axoneme to shift its behavior to one characteristic of a higher pCa: TFP inhibited backward swimming in models reactivated at pCa 〈 6; instead they swam forward or rocked in place. The mechanism of ciliary reversal in paramecium may therefore depend on an axonemal Ca+-sensor, possibly bound CaM, which is affected by TFP only at low pCa, as has been postulated for other types of cilia.
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    Cell Motility and the Cytoskeleton 1 (1981), S. 193-203 
    ISSN: 0886-1544
    Keywords: polygonal network ; rat aortic smooth muscle cell ; cell culture ; electron microscopy ; amino acid analysis ; elastin ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Cultured rat aortic smooth muscle cells (SMC) were examined by electron microscopy and found to contain polygonal networks of 75 A° thin myofilament bundles. The cells also had large bundles of longitudinally aligned thin myofilaments with periodically spaced dense bodies. Abundant plasmalemmal vesicles were present at the cell periphery, and the cells were connected by desmosomes. Intercellular spaces contained sparse amounts of elastic fibers, a material generally present in SMC cultures. Analyses of amino acids by automated column-chromatography showed that isodesmosine and desmosine, two amino acid residues unique for elastin, were present. Accordingly, it was concluded that polygonal networks, previously detected solely in cultured nonmuscle cells, were present in SMC.Other findings suggest (1) a change in myofilament arrangement takes place during cell migration, and (2) rat aortic SMC grown in tissue culture flasks is an important experimental tool in the study of cell motility since such myofilament rearrangements were observed to occur up to fourteen days in first passage.
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    Cell Motility and the Cytoskeleton 1 (1981), S. 179-192 
    ISSN: 0886-1544
    Keywords: actin ; echinoderm ; fascin ; filopodia ; actin cross-linking protein ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Echinoderm coelomocytes transform from petaloid cells with large motile lamellipodia to filopodial forms. During this morphological transformation, actin filaments extensively reorganize from a random meshwork into tight bundles, which become the skeletons or cores of the filopodia. Antibody localization procedures show that fascin, a 58,000 dalton actin cross-linking protein, becomes incorporated into the filament bundles as they form. Isolated filopodial cores have a pronounced transverse striping pattern, which has been previously identified with fascin crosslinks, and gel electrophoresis identifies a protein in the cores that co-migrates with purified egg fascin. A few of the core fragments also have a distinctive “cap,” which we presume is the membrane insertion site for actin filaments.We have developed a radioimmunoassay for fascin and have used it to study the redistribution of this protein during transformation. Data from the assay indicate that fascin constitutes about 5% of the total cell protein and that substantially more fascin, approximately 1.5-2 times more, is found in the Triton-insoluble cytoskeletons of the filopodial cells than in the petaloid cells. Actin, measured by the DNAase I inhibition assay accounts for approximately 10% of the total cell protein. Approximately 65% of this actin is in a soluble non-filamentous form in the petaloid cells. Our results show that actin polymerization must occur during the cell shape change, since we find approximately 25% more actin in the filopodial cytoskeleton than in the petaloid cytoskeleton. The results show a preferential incorporation of fascin into the cytoskeleton as the cells form filopodia.
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    Cell Motility and the Cytoskeleton 1 (1981), S. 205-235 
    ISSN: 0886-1544
    Keywords: capping of receptors ; cell locomotion ; cell-surface interactions ; frictional force ; membrane flow ; polymorphonuclear leukocytes ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: As a cell moves over a surface, the distribution of membrane proteins that adhere to the surface will be changed relative to the distribution of these molecules on a static cell. Observations of this redistribution offer, in principle, evidence as to the mechanisms of membrane dynamics during cell locomotion. Toward extracting such information we present and analyze a mathematical model of receptor transport in the membrane by diffusion and convection, as affected by the making and breaking of the bonds between the receptors and the surface as the cell moves.We show that the disruption of receptor-surface bonds at the tail of the cell provides a mechanism by which the frictional force opposing a cell's motion is exerted, and calculate the magnitude of this force as a function of cell velocity. Assuming this to be the major contribution to the frictional force, we show that when the shear force on a cell is above a critical value it is no longer possible for the cell to slide across the surface. For such large forces, it is still possible for the cell to roll; alternatively the cell can be torn free of the surface.Our analysis of existing data on movement of polymorphonuclear leukocytes indicates that cell motion is not accompanied by a bulk flow of membrane from the front to the back of the cell. The data also indicate that cells do not tend to roll as they move over a surface under normal conditions. The data are most consistent with a model where the membrane as a whole is stationary but where receptors that bind to the surface become coupled to sub-membrane contractile proteins.
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    Cell Motility and the Cytoskeleton 1 (1981), S. 269-272 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Cell Motility and the Cytoskeleton 1 (1981), S. 261-268 
    ISSN: 0886-1544
    Keywords: Tetrahymena ; chemotaxis ; temporal-gradient sensing ; modulation of turning frequency ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The motility pattern of Tetrahymena thermophila in a homogeneous attractant field consists of successive “runs” and “turns.” The turning frequency decreases or increases upon an abrupt increase in attractant or repellent concentration, respectively. The dose-response curve for leucine and methionine yields a saturation curve with half maximum modulation of the turning frequency at a concentration of 15 μM and 2 μM, respectively. The turning frequency is modulated at a threshold concentration of 0.02 μM and 0.50 μM for leucine and methionine, respectively. The decrease (increase) in turning frequency in the presence of an attractant (repellent) jump reverts to prestimulus frequency in a time proportional to the concentration jump. Hence, Tetrahymena seem to employ temporal-gradient sensing for chemotaxis. Spatial-gradient taxis is thus exerted by random walk, which is biased in the direction of the gradient.
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    Cell Motility and the Cytoskeleton 1 (1981), S. 237-245 
    ISSN: 0886-1544
    Keywords: centrioles ; symmetry ; triplet blades ; thermal fluctuations ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The paper suggests several principles of construction of a microscopically small device for locating the directions of signal sources in microscopic dimensions. It appears that the simplest and smallest device that is compatible with the scrambling influence of thermal fluctuations as are demonstrated by Brownian motion is a pair of cylinders oriented at right angles to each other. Nine equally spaced blades run in a pitched fashion along the mantle of each cylinder. The blades have a concave cross-section and bend around the circumference of the cylinder in a certain rotational pattern. Considering the striking similarity of this hypothetical device with centrioles, the paper puts forward the conjecture that centrioles locate the direction of hypothetical signals inside cells.
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    Cell Motility and the Cytoskeleton 1 (1981), S. 247-260 
    ISSN: 0886-1544
    Keywords: cilia ; trachea ; ATP-reactivation ; ciliary activity ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Evidence for active sliding of microtubules during ciliary activity has been demonstrated in a number of organisms: sea urchin sperm flagella, protozoan cilia, and mollusc gill cilia. Although there is evidence that active sliding also occurs in mammalian sperm flagella, there is little or no information on whether active sliding of microtubules also occurs in the short (5-μm) cilia of the mammalian trachea or oviduct. Since these cilia are important in tracheobronchial clearance and ovum transport, respectively, it has been important to demonstrate that microtubule sliding is also involved in the activity of somatic cilia. Ciliated apical portions (cortices) and cilia were isolated from rabbit trachea and oviduct, using Triton X-100 to demembranate the cilia. Most of the ciliated cortices reactivated upon addition of ATP, whereas isolated cilia reactivated to a lesser extent. When preparations of cilia were digested with trypsin before or after ATP addition, disintegration of axonemal doublets occurred with about the same frequency as reactivation. These events were recorded using Nomarski optics and dark-field microscopy. When isolated cilia which had been digested by trypsin and exposed to ATP were also prepared for electron microscopy by negative staining, telescoping of doublet microtubules from axonemes could be shown. These results demonstrate that mammalian somatic ciliary doublet microtubules actively slide in a manner similar to that described for invertebrate cilia.
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    Cell Motility and the Cytoskeleton 1 (1981), S. 273-273 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Cell Motility and the Cytoskeleton 1 (1981) 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Cell Motility and the Cytoskeleton 1 (1981), S. 371-385 
    ISSN: 0886-1544
    Keywords: rotating filaments ; cytoplasmic streaming ; Nitella ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Our knowledge about the actin-containing characean filaments on the basis of light and electron microscopical investigations is reviewed. Dynamic filamentous networks, known already from isolated droplets, were detected in Nitella rhizoidal cells using light microscopical techniques. Earlier light microscopic observations in cytoplasmic droplets are confirmed and complemented by new model experiments with rotating helices. The motile phenomena occurring at the filament bundles (ring formation, wave propagation, particle translocation, net dynamics, rolling motions, formation of side arms) can, in this way, be imitated in detail. Thus, the concept of cytoplasmic streaming as a translocation along bundles of rapidly rotating helical filaments is supported. In order to explain unidirectional cytoplasmic streaming, a periodic winding up and unwinding of fine filaments is postulated by which ions are periodically bound and displaced. The formation of side arms which is favored during unwinding results in a screw-mechanical different behavior of the filaments in the two directions of rotation and therefore causes permanent particle transport in one direction.
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    Cell Motility and the Cytoskeleton 1 (1981), S. 387-397 
    ISSN: 0886-1544
    Keywords: birefringence ; polarizing microscope ; sea urchin egg ; cortex ; mitosis ; cleavage ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Birefringence (BR) at the cell surface of fertilized eggs of the sand-dollar, Clypeaster japonicus, during mitosis and cleavage was determined with a photoelectric BR detection apparatus [Hiramoto et al, 1981a]. The cortex of about 2 μm thickness is birefringent positive with respect to the normal to the cell surface. The hyaline layer is negatively birefringent. The halo-layer consisting of a row of microvilli surrounding the egg is positively birefringent in normal Ca-free sea water, while it is negatively birefringent in Ca-free sea water with high refractive index. The BR of the cortex gradually increases over the entire surface during mitosis until the onset of cleavage. The BR of the cortex at the polar region reaches a maximum shortly after the onset of cleavage and then decreases, while the BR of the cortex at the equatorial region begins to decrease shortly before the onset of cleavage, reaches a minimum shortly after the cleavage starts, and then increases again as the cleavage furrow advances. The coefficient of birefringence of the cortex is about 2.5 × 10-5 at the maximum. The BR change of the cortex during mitosis and cleavage is interpreted as a passive deformation caused by the constriction of the contractile ring as well as an active structural change of the cortex occurring in the dividing cell.
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    Cell Motility and the Cytoskeleton 1 (1981), S. 399-416 
    ISSN: 0886-1544
    Keywords: myosin heavy chain ; avian muscular dystrophy ; adult and embryonic fast white fibers ; slow red fiber ; rod ; subfragment-1 ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Avian muscular dystrophy is characterized by the degeneration of fast white skeletal muscle fibers, with onset during development. Using a one-dimensional peptide mapping technique, we have detected two forms of the myosin heavy chain in the fast white fibers of adult domestic chickens, one form characteristic of birds homozygous for muscular dystrophy, the other of their normal controls. Four dystrophic strains carrying the same gene for muscular dystrophy were examined.No differences were detected in the embryonic heavy chain peptide maps of normal and dystrophic chickens, consistent with the developmental onset of the condition. Differences were also absent from the peptide maps of heavy chains from slow red fibers, which are unaffected in dystrophy. No dystrophy-specific peptide map differences were detected in the three light chains. Analysis of peptide maps of rod and the heavy chain component of subfragment-1 from normal and dystrophic heavy chains indicates the presence of amino acid sequence differences in the two proteins.
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  • 192
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    Cell Motility and the Cytoskeleton 1 (1981), S. 417-431 
    ISSN: 0886-1544
    Keywords: spindle poles ; centrioles ; cell center ; scaffold ; electron microscopy ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: I have used fluorescence microscopy and antibodies to 10nm filaments and tubulin labelled with contrasting fluorochromes to compare the distribution of these proteins in endothelial cells during cell division. During interphase the two filament systems have entirely different distributions: The bulk of the 10nm filaments form a ring that surrounds the cell center and nucleus and remains parallel to the substrate, while the microtubules radiate from the cell center to the cell's border. When the mitotic spindle replaces the radial microtubule pattern in mitosis, the spindle poles remain within - and in close proximity to - the ring of 10nm filaments. This was confirmed by electron microscopy which showed the ring and centrioles in the same plane separated by a distance of 300-400 nm.
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  • 193
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    Cell Motility and the Cytoskeleton 4 (1984), S. 121-128 
    ISSN: 0886-1544
    Keywords: axonal transport ; ATP ; nucleotides ; saltatory movement ; dynein ; video microscopy ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In a permeabilized axon model, exogenous ATP can reactivate intraaxonal saltatory organelle movements (microscopically visible manifestations of fast axonal transport). We have studied the dependence of the reactivated movements on the ATP concentration and have also examined the nucleotide specificity of the reactivation. Organelle transport was visualized in isolated lobster giant motor axons using Nomarski optics and video microscopy. The axons were permeabilized with saponin, and movement was reactivated with ATP or other nucleotides. Some slight movement was seen with ATP concentrations as low as 10 μM. The velocity and frequency of the reactivated transport increased with increasing ATP concentrations up to about 5 mM. Movement was also reactivated by deoxyadenosine triphosphate, but not by AMP-PNP (a nonhydrolyzable ATP analogue), ADP, or AMP. Although other nucleotides (CTP, GTP, UTP, ITP) could reactivate transport, movement equivalent to that produced by 0.1 mM ATP was only seen with tenfold or greater concentrations of the other nucleotides. This pattern of specificity is consistent with the hypothesis that a dynein-like ATPase, rather than a myosin, is involved in fast axonal transport.
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  • 194
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    Cell Motility and the Cytoskeleton 4 (1984), S. 137-149 
    ISSN: 0886-1544
    Keywords: anti-fluorescein ; fluorescent analog cytochemistry ; molecular cytochemistry ; microinjection ; actin ; acetamidofluorescein-actin ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Fluorescent analogs of cellular components are finding increasing use in the field of cell biology. The power of this technique can be augmented by the use of antibodies specific for the fluorophore to visualize selectively the fluorescent analog at the electron microscope level. Rabbit antibodies specific for fluorescein were elicited and purified according to published methods (Lopatin and Voss [1971]: Biochemistry 10:208). Immune sera and IgG formed precipitin lines with fluorescein-labeled proteins in Ouchterlony immunodiffusion assays, and significantly quenched the fluorescence of fluorescein-labeled proteins. Immune IgG and Fab fragments decorated fluorescein-labeled actin, but not unlabeled actin, in negative-stained preparations. Anti-fluorescein IgG was used for immunofluorescent localization of fluorescein-labeled actin following microinjection of the fluorescent analog into living cells. This approach was extended to the immunoelectron microscopic localization of the injected analog at the subcellular level by the use of an electron-dense marker coupled to goat anti-rabbit IgG. Many other fluorescent probes also can be used as haptens for production of antibodies. Therefore, a general method for localizing fluorescently labeled molecules at the electron microscopic level is now available. Several other applications of anti-fluorescein antibody in studies involving fluorescent analogs are also suggested.
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  • 195
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    Cell Motility and the Cytoskeleton 4 (1984), S. 183-196 
    ISSN: 0886-1544
    Keywords: tubulin ; assembly ; mitotic apparatus ; bimane ; fluorescence microscopy ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Fluorescent derivatives of cellular proteins that retain their native characteristics have become useful probes to investigate the dynamics of specific cytoskeletal proteins. In the experiments reported here, a previously characterized fluorescent derivative of tubulin, bimane-tubulin [Wadsworth and Sloboda, 1982a], was used to investigate microtubule assembly in vitro. The results demonstrate that bimanetubulin was competent to assemble onto a variety of organizing centers in vitro, including microtubule organizing centers (MTOCs) present in homogenates of sea urchin eggs, isolated mitotic apparatuses (MAs), and lysed mitotic cells. When homogenates of fertilized sea urchin eggs containing MTOCs were incubated with bimane-tubulin at 37°C, discrete areas of linear fluorescence were observed. Only diffuse fluorescence was observed when calcium or colchicine was added to the homogenate or if the temperature was maintained at 0°C. Negative-stain electron microscopy of the fluorescent arrays revealed morphologically normal microtubules radiating from electron dense regions. When mitotic spindles, isolated in glycerol containing buffers and therefore cold stable, were incubated with bimane-tubulin, linear fluorescence was observed emanating from the spindle poles but not from the region occupied by the kinetochores. MAs incubated with bimane-labeled bovine serum albumin or bimane-labeled microtubule-associated proteins showed only diffuse fluorescence. However, when mitotic cells which were hypotonically lysed in the absence of detergents or microtubule stabilizing solvents, were perfused with bimane-tubulin intense fluorescence was observed in the asters and throughout the spindle. Two experiments suggested that the fluorescence observed in the results outlined above was due to the assembly of normal microtubules from the fluorescent subunits. First, the observed fluorescence was sensitive to cold temperataure, which is known to disassemble microtubules. Second, when the isolated, fluorescent MAs were examined by thin section electron microscopy, microtubules of normal diameter were seen. No aggregated material appeared associated with the walls of the microtubules, which might have been expected if the fluorescent protein was nonspecifically adsorbed to the microtubules. The results of these experiments demonstrate that isolated, stabilized MAs support the growth of new microtubules from the spindle poles while labile spindles, present in lysed cells, incorporate fluorescent tubulin throughout the spindle and asters. The significance of these results for hypotheses concerning microtubule assembly and disassembly during mitosis is discussed.
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  • 196
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    Cell Motility and the Cytoskeleton 4 (1984), S. 241-247 
    ISSN: 0886-1544
    Keywords: cytoskeleton ; centrosome ; tonofilaments ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We present observations on the relative location of the centriole and keratin filament cap in motile PtK1 cells. Subconfluent cells were double labeled with anticentriole and antikeratin sera. These preparations revealed that the centriole is separate from, but neighboring, the keratin filament cap. Serial ultrathin sections confirm this observation. These observations are consistent with the idea that the microtubule organizing center and intermediate filament distribution center are not identical or concentric in PtK1 cells.
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  • 197
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    Cell Motility and the Cytoskeleton 4 (1984), S. 269-281 
    ISSN: 0886-1544
    Keywords: microtubules ; microfilaments ; filopodia ; cell spreading ; coelomocytes ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Sea urchin coelomocytes were used as a model system to investigate the distribution and role of microtubules and microfilaments in cell spreading and filopodial formation. By using immunoblot characterized antisera to tubulin and actin coupled with immunofluorescence techniques, cellular protrusions were seen to contain actin filaments but no microtubules. Cells depleted of MT's by cold and colcemid treatments could attach, spread, and transform to the filopodial morphology normally.
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  • 198
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    Cell Motility and the Cytoskeleton 4 (1984), S. 231-239 
    ISSN: 0886-1544
    Keywords: pseudostereoscopy ; particle speed distribution ; velocity distribution ; fast axonal transport ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We describe a simple method for direct visualization of the velocity distribution of particles moving against an immobile background. The technique involves pseudostereoscopic viewing of image pairs separated by an appropriate time interval in a sequential recording of the subject. Under these conditions, the positive or negative parallax arising from particle motion results in the binocular image of a particle being perceived as raised or lowered relative to an immobile background plane depending on its direction of movement, and with the degree of perceived elevation being proportional to its speed. In effect, the binocular optic axis becomes a velocity (speed) axis under these conditions. The technique is illustrated with examples of image pair sequences showing fast axonal transport in lobster and squid axons using video-enhanced differential interference contrast microscopy. However, the pseudostereoscopic method is quite generally applicable to both microscopic and macroscopic time-dependent phenomena. Particle speeds can be quantitated using standard procedures for measuring frame-to-frame particle displacements, or alternatively, by determination of parallax using stereogrammatic methods. It should be also readily adaptable for on-line monitoring of particle velocity distribution, particularly in video systems where frame buffers can be utilized to extract and present serial image pairs having any desired time separation from video-taped sequences.
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  • 199
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    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 283-295 
    ISSN: 0886-1544
    Keywords: axonemal mutants ; Ca++ response ; ciliary reversal ; electrophysiology ; models ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Six mutants of Paramecium tetraurelia, which display altered axonemal responses to Ca++, are described. The mutants, designated atalantas, are impaired in their ability to swim backward when stimulated by ions or heat; instead they spin very rapidly in one place. Three mutants, ataA1-3, are completely unable to swim backward. The three lines, however, can be distinguished from one another by their forward swimming velocities. The remaining three mutants are leaky. ataB swims backward briefly when stimulated, then stops and spins in place. ataC and ataD are extremely leaky and only display the spinning phenotype at elevated temperatures. An electrophysiological analysis reveals that all six mutants have normal membrane properties, including the Ca++ inward current under voltage clamp. When the membrane is disrupted so as to allow the axoneme free access to Ca++, wild-type cells swim backward, but the mutants do not. These data indicate the site(s) of lesion in the mutants is in the axoneme or in some step linking Ca++ influx and the axoneme, not within the ciliary membrane. These mutants may be useful in investigating the role of Ca++ in the regulation of axonemal motion.
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  • 200
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    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 297-303 
    ISSN: 0886-1544
    Keywords: exocytosis ; chromaffin cells ; vesicle release ; light microscope ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Cultured bovine adrenal medullary chromaffin cells were stimulated with the secretogogues Ba2+ or carbamyl choline plus Ca2+. With video-enhanced contrast, differential interference contrast microscopy, small vesicles were found to appear on the cell surface during stimulation. The structures were of lower refractive index than the cytoplasm, and their appearance required several tenths of a second. The vesicles are thought to correspond to omega figures seen with electron microscopy due to exocytosis. Many of the structures disappeared within a few seconds, but some appeared to coalesce into larger structures. The large structures may lead to the vacuoles that have been demonstrated to be present following stimulation. The nature of the cellular elements responsible for the vesicle which appeared on the surface was not found with either differential interference or interference reflection microscopy. The simplest explanation is that the refractive index of the elements is similar to that of the cell, and therefore the elements cannot be seen.
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