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  • Electron microscopy  (378)
  • Springer  (378)
  • American Geophysical Union
  • Irkutsk : Ross. Akad. Nauk, Sibirskoe Otd., Inst. Zemnoj Kory
  • Krefeld : Geologischer Dienst Nordhein-Westfalen
  • Wiley
  • 2005-2009
  • 1975-1979  (378)
Collection
Keywords
Publisher
  • Springer  (378)
  • American Geophysical Union
  • Irkutsk : Ross. Akad. Nauk, Sibirskoe Otd., Inst. Zemnoj Kory
  • Krefeld : Geologischer Dienst Nordhein-Westfalen
  • Wiley
    • +
Years
Year
  • 1
    Electronic Resource
    Electronic Resource
    Time-related changes in the ultrastructure of osteoclasts after injection of parathyroid hormone in young rats (1979)
    Springer
    Calcified tissue international 27 (1979), S. 129-135 
    Details
    ISSN: 1432-0827
    Keywords: Parathyroid hormone ; Osteoclasts ; Electron microscopy ; Morphometry ; Metaphysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The effects of parathyroid hormone (PTH) on the size of the osteoclasts, nuclei, ruffled borders, and clear zones in long bones of thyroparathyroidectomized (TPTX) rats were quantitated as a function of time. These data were compared with the number of osteoclasts in the bone and with plasma calcium levels. A significant increase in the average size of the ruffled borders was demonstrated 30 min after injection of 50 U of purified bovine PTH, and of the clear zones 30–90 min after PTH. This was followed at 90 min by an increase in the average size of the cells. The sizes of ruffled borders and clear zones dropped sharply to control levels after 6 h, whereas the size of the cells remained elevated up to 12 h and returned to control values at 24 h. Plasma calcium levels were increased, but not significantly, between 30 min and 6 h. An increase in the number of osteoclasts was significant after 12 h. Removal of the parathyroid glands did not diminish the normal activity of osteoclasts. In animals with intact glands injection of 50 U of PTH did not cause a significant change in cell size or resorbing apparatus. It is concluded that PTH acts to rapidly stimulate the bone resorptive activity of osteoclasts and to cause a delayed increase in their number.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02441175
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  • 2
    Electronic Resource
    Electronic Resource
    Orientation of apatite in single osteon samples as studied by pole figures (1979)
    Springer
    Calcified tissue international 29 (1979), S. 101-105 
    Details
    ISSN: 1432-0827
    Keywords: Osteon ; X-ray diffraction ; Pole figures ; Electron microscopy ; Calcification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The X-ray diffraction method based on pole figures has been applied to single osteon samples in order to obtain information about the texture of the inorganic bone fraction and the way it changes during calcification. The osteon samples were cylindrically shaped, with axes corresponding to those of the haversian canals. Selection was carried out according to the degree of calcification and the orientation of collagen bundles and inorganic particles. Osteons at both the initial and final stages of calcification were chosen. Arrangements of fiber bundles and inorganic particles in successive lamellae characteristic of three types of osteons were selected: longitudinal, alternate, and transversal. The results indicate that in all three types of osteons, the long axis of the sample is apparently the only direction of orientation because the transversally oriented crystallites give an isotropic diffuse scattering as would be expected if all the inorganic particles were irregularly oriented around the osteon axis. The number of longitudinally oriented crystallites increases progressively from transversally oriented osteons to alternately and longitudinally oriented ones. The crystallite orientation in an axial direction increases in fully calcified osteons. This last result is in agreement with the electron microscopic finding that the long needle-shaped crystallites covering much more than a major collagen period and measuring 40–45 Å in width increase in number as calcification proceeds.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02408064
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  • 3
    Electronic Resource
    Electronic Resource
    Acetobacter bacteriophage A-1 (1979)
    Springer
    Archives of microbiology 121 (1979), S. 193-197 
    Details
    ISSN: 1432-072X
    Keywords: Acetobacter suboxydans ; Bacteriophage A-1 ; Restriction ; Modification ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A bacteriophage ofAcetobacter suboxydans was isolated and found to correspond to type A phage according to Bradley's classification. The phage contains double stranded DNA. The length of the latency period and burst size could not be precisely determined because of apparent non-synchronous release of phage from single infective cycles. The host range was determined using 24 strains ofAcetobacter andGluconobacter species. Evidence for a probable occurence of host determined restriction and modification was obtained withAcetobacter suboxydans strain ATCC 621. The phage is designated A-1 and it is the first one to be reported forAcetobacter.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00689986
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  • 4
    Electronic Resource
    Electronic Resource
    R-Bodies in newly isolated free-living hydrogen-oxidizing bacteria (1979)
    Springer
    Archives of microbiology 121 (1979), S. 9-15 
    Details
    ISSN: 1432-072X
    Keywords: R-Bodies ; Kappa particles ; Free-living hydrogen bacteria ; Induction ; Electron microscopy ; Chemical composition ; Defective prophages ; Plasmids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract R-Bodies have been found in a recently isolated pseudomonas-like free-living hydrogen oxidizing bacterium. Their isolation, fine structure and chemical composition are described and compared with the R-bodies from the kappa particles (Caedobacter), obligate endosymbionts of Paramecium aurelia. The 2K 1 R-bodies exhibited essential characteristics of the kappa R-bodies; however, their size and some other structural aspects proved that they represent a new type of R-bodies. The presence of phage tail-like particles in cells induced with Mitomycin C is in favour of the hypothesis that the R-bodies might be coded by defective prophages, or by extrachromosomal elements.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00409199
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  • 5
    Electronic Resource
    Electronic Resource
    Bdellovibrio-like parasite of cyanobacteria symbiotic in marine sponges (1979)
    Springer
    Archives of microbiology 123 (1979), S. 101-103 
    Details
    ISSN: 1432-072X
    Keywords: Bdellovibrio ; Cyanobacteria ; Marine sponges ; Symbiosis ; Infection ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A bdellovibrio-like bacterium was observed infecting unicellular symbiotic cyanobacteria in two coral reef sponges, Neofibularia irata and Jaspis stellifera. The infecting bacterium, which was located between the cell wall and the cytoplasmic membrane of the cyanobacteria, was similar in size and appearance to previously described bdellovibrios. This observation is believed to extend the host range of the bdellovibrios.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00403507
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  • 6
    Electronic Resource
    Electronic Resource
    Electron microscopic study on the quaternary structure of the isolated particulate alcohol-acetaldehyde dehydrogenase complex and on its identity with the polygonal bodies of Clostridium kluyveri (1979)
    Springer
    Archives of microbiology 120 (1979), S. 255-262 
    Details
    ISSN: 1432-072X
    Keywords: Alcohol dehydrogenase ; Acetaldehyde dehydrogenase ; Clostridium kluyveri ; Electron microscopy ; Polygonal bodies ; Enzyme complex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The alcohol-acetaldehyde dehydrogenase complex of Clostridium kluyveri has been separated from contaminating β-hydroxybutyryl-CoA dehydrogenase by repeated precipitation with manganese and ammonium sulfate. Mn++ was required for maximum alcohol dehydrogenase activity. The molecular weight of the enzyme complex was 194,000 as determined by sucrose density gradient centrifugation. The enzyme complex has been shown to contain two types of subunits with molecular weights of 55,000±2,600 and 42,000±1,200, respectively which are arranged in “H”-shaped particles. In solutions with an ionic strength above 25 mM the enzyme complex precipitated in the form of lumps as has been shown with specific ferritin-conjugated antibodies. These lumps are assumed to be aggregated polygonal bodies present in C. kluyveri.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00423073
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  • 7
    Electronic Resource
    Electronic Resource
    The cell cycle of Bacillus subtilis as studied by electron microscopy (1979)
    Springer
    Archives of microbiology 123 (1979), S. 173-181 
    Details
    ISSN: 1432-072X
    Keywords: Bacillus subtilis ; Cell cycle ; DNA replication ; Cell division ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Bacillus subtilis strain Marburg was grown exponentially with a doubling time of 65 min. To follow the time course of various cell cycle events, cells were collected by agar filtration and were then classified according to length. The DNA replication cycle was determined by a quantitative analysis of radioautograms of tritiated thymidine pulse labeled cells. The DNA replication period was found to be 45 min. This period is preceded and followed by periods without DNA synthesis of about 10 min. The morphology and segregation of nucleoplasmic bodies was studied in thin sections. B. subtilis contains two sets of genomes. DNA replication and DNA segregation seem to go hand in hand and DNA segregation is completed shortly after termination of DNA replication. Cell division and cell separation were investigated in whole mount preparations (agar filtration) and in thin sections. Cell division starts about 20 min after cell birth; cell separation starts at about 45 min and before completion of the septum.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00446817
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  • 8
    Electronic Resource
    Electronic Resource
    Ultrastructural morphometry of blastogenesis I: Transformation of small lymphocytes stimulated in vivo with dinitrochlorobenzene (1979)
    Springer
    Cell & tissue research 200 (1979), S. 495-509 
    Details
    ISSN: 1432-0878
    Keywords: T-lymphocytes ; Blast cells ; Lymph node ; Electron microscopy ; Stereology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Changes in the volumes and surfaces of subcellular compartments of unstimulated small lymphocytes and immunoblasts in mouse axillary lymph nodes have been established using stereological techniques. Blast transformation was induced in vivo with dinitrochlorobenzene (DNCB). Cell samples were obtained by random sampling regimes applied at light and electron microscopic levels. From electron micrographs the volume densities of euchromatin, heterochromatin, nucleoli, mitochondria, Golgi apparatus and rough endoplasmic reticulum were determined. Cell surface/volume ratios were also computed. By estimating mean nuclear volumes using light microscopy, it was possible to calculate absolute compartmental volumes and to evaluate the plasma membrane surface areas of average cells. Transformation in this model was characterized by a considerable cellular hypertrophy and a substantial increase in plasmalemma surface. Hypertrophy was the consequence of increases in the volumes of all measured intracellular compartments, notably euchromatin and “residual cytoplasm” (including ground cytoplasm and free ribosomes). These changes are discussed in the context of the altered metabolic status of cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00234859
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  • 9
    Electronic Resource
    Electronic Resource
    A new morphological aspect of the brush cells of the mouse gallbladder epithelium (1979)
    Springer
    Cell & tissue research 201 (1979), S. 37-44 
    Details
    ISSN: 1432-0878
    Keywords: Brush cell ; Receptor ; Lateral microvilli ; Gallbladder ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The brush cells of the gallbladder epithelium of the mouse have microvilli not only at their luminal border but also on their lateral surface, from the level of the nucleus to the junctional complex. The lateral microvilli radiate from the brush cell in all directions, contain a core of filaments, and penetrate up to 3 μm into the adjacent cells. The microvilli in these locations display small desmosomes at their base.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00238045
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  • 10
    Electronic Resource
    Electronic Resource
    Activation of human T-lymphocytes (1979)
    Springer
    Cell & tissue research 201 (1979), S. 101-127 
    Details
    ISSN: 1432-0878
    Keywords: T-lymphocytes ; Cell activation ; Stereology ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Stereological data of phytohaemagglutinin (PHA)-activated human T-lymphocytes were recorded at intervals (12 to 72 h) together with biochemical (isotope-uptake, lymphotoxin-release) and morphological measurements. About 98 % of the cells were activated 12 h after PHA-stimulation. The activation phase lasted less than 48 h, i.e., cells entering the activation phase within 12 h were at their activation maximum by 48 h. The activated cell increased in size. The nuclear/cytoplasmic-ratio decreased. Most of the cytoplasmic organelles developed in phase with the increase of cytoplasmic volume. After 48 h, mitotic figures were frequently seen. Due to the increasing number of secondary, activated daughter cells, parameters of most cytoplasmic components declined between 48 and 72 h. Structural changes in the nucleus preceded the 3H-leucine uptake, which had not reached its maximum after 72 h of incubation. The 3H-leucine uptake started as early as 12 h after culture initiation, and its increase was proportional to the increasing polyribosome density. No maximum uptake was reached up to 72 h, but the development of structural components related to this uptake was at its maximum at the end of the activation phase (48 h). The formation of bound ribosomes occurred subsequent to the enlargement of the surface of the rough endoplasmic reticulum. Initial polysome formation occurred at the expense of existing free ribosomes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00238051
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  • 11
    Electronic Resource
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    Ultrastructural responses of pancreatic β cells to metabolic alkalosis (1979)
    Springer
    Cell & tissue research 201 (1979), S. 159-163 
    Details
    ISSN: 1432-0878
    Keywords: Insulin secretion ; Acid-base changes ; Electron microscopy ; Pancreas perfusion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructural changes in pancreatic β cells were studied following glucose-induced insulin secretion in vitro, at two different extracellular pH (7.4 and 7.8). The pancreata perfused at pH 7.4 exhibited a biphasic insulin response to glucose challenge together with signs of increased emiocytotic activity and numerous microtubules in the β cells. Conversely, the pancreata perfused at pH 7.8 showed a significant decrease in insulin secretion, and their β cells revealed scarce emiocytotic images and a marked increase of intracellular granulolysis. These results represent the ultrastructural correlate of the reduced insulin secretion produced by metabolic alkalosis in the perfused rat pancreas.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00238055
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  • 12
    Electronic Resource
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    Fine structure of the rabbit adrenal cortex and the effects of short-term ACTH administration (1979)
    Springer
    Cell & tissue research 201 (1979), S. 165-179 
    Details
    ISSN: 1432-0878
    Keywords: Adrenal cortex ; Steroid release ; Rabbit ; Electron microscopy ; Morphometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The fine structure of the rabbit adrenal cortex was investigated. The parenchymal cells display the ultrastructural features of steroid-producing cells, and also contain numerous electron-dense bodies frequently located near intercellular canaliculi, which open into the subendothelial space. Short-term ACTH-administration induced a noticeable decrease in the volume of the lipid compartment in the cells of all three cortical zones and a significant increase in the volume of dense bodies in the cells of zona fasciculata and zona reticularis. The hypothesis that these dense bodies are secretory granules is discussed in the light of biochemical evidence showing that ACTH increases the concentration of both corticosterone and cortisol in the decapsulated-enucleated adrenal homogenate and does not affect the activity of two lysosome-marker enzymes (i.e., acid phosphatase and β-glucuronidase).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00235055
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  • 13
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    An ultrastructural study of macrophage-mediated resorption of calcified tissue (1979)
    Springer
    Cell & tissue research 202 (1979), S. 125-132 
    Details
    ISSN: 1432-0878
    Keywords: Macrophage ; Osteoclast ; Bone resorption ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Ultrastructural observations on macrophage-mediated resorption of calcified tissue of killed fetal long bones are described and correlated with increased 45Ca release into the medium. Macrophages disrupt calcified tissue extracellularly and appear to engulf large fragments of mineralized matrix. Ruffled borders, which are common features of osteoclasts at sites of resorption of bone, do not develop in macrophages. However, clear zones are seen in macrophages as well as osteoclasts. These findings provide additional evidence for non-osteoclast-mediated resorption of calcified tissue.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00239225
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  • 14
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    Ultrastructural changes in neurohaemal tissue of the stick insect, Carausius morosus, induced by the ionophores Br-X-537 A and A-23187 (1979)
    Springer
    Cell & tissue research 197 (1979), S. 227-234 
    Details
    ISSN: 1432-0878
    Keywords: Neurosecretory granules (Insects) ; Ionophores ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The antibiotic ionophores Br-X-537A and A-23187 alter the ultrastructure of neurohaemal tissue on the transverse nerve of the stick insect, Carausius morosus. Br-X-537A induces dramatic changes in the ultrastructural appearance of all three types of neurosecretory fibres present in the neurohaemal tissue. The neurosecretory granules become more electron-lucent and the mitochondria become more electron-opaque. The bounding membrane of the granules is frequently ruptured. A-23187, on the other hand, has no effect on two of the three types of fibres, but does produce an increase in the number of exocytotic profiles in the third. The two ionophores therefore have different effects on the same tissue. The results are discussed in the light of previous work with the use of these ionophores.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00233916
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  • 15
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    Electron microscopic study of the termination of the centrifugal fibers in the goldfish olfactory bulb (1979)
    Springer
    Cell & tissue research 197 (1979), S. 257-262 
    Details
    ISSN: 1432-0878
    Keywords: Centrifugal fibers ; Olfactory bulb ; Goldfish ; Degenerating synapses ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The terminals of centrifugal fibers to the olfactory bulbs of goldfish were studied by electron microscopy after transection of the medial, lateral or entire olfactory tract. The centrifugal fibers originate in the telencephalic hemisphere, pass through both the medial and the lateral olfactory tract, and form synaptic contacts with dendrites in the granule cell layer.
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    URL: http://dx.doi.org/10.1007/BF00233918
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  • 16
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    The osteoclast-endothelium interface during bone resorption in the femurs of young rabbits (1979)
    Springer
    Cell & tissue research 203 (1979), S. 487-492 
    Details
    ISSN: 1432-0878
    Keywords: Osteoclasts ; Endothelium ; Bone resorption ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The morphological relationship between the osteoclasts at the endosteal surface of two-week-old rabbit femurs and the endothelium of vascular channels of the bone marrow was examined. Light microscopy revealed that 85% of the osteoclasts make direct contact with the endothelial cells. The ultrastructure of this osteoclast-endothelium interface shows that the osteoclast has specialized processes which reach out towards the endothelial cells coming into close proximity with them. On rare occasions, specialized junctions between these processes and the endothelial cells are noted.
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    URL: http://dx.doi.org/10.1007/BF00233276
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  • 17
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    Ultrastructural evidence for disuse atrophy in insect skeletal muscle (1979)
    Springer
    Cell & tissue research 203 (1979), S. 503-506 
    Details
    ISSN: 1432-0878
    Keywords: Muscle ; Disuse atrophy ; Insects ; Ultrastructure ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The changes which occur in the ultrastructure of the mesothoracic retractor unguis muscle of the cockroach Periplaneta americana as a result of disuse are described. Breakdown of myofibrils, sarcoplasmic reticulum, and mitochondria are all marked, this degeneration only being apparent 9 weeks after the operation.
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    URL: http://dx.doi.org/10.1007/BF00233279
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  • 18
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    Electron microscopic immunocytochemical demonstration of separate vasotocinergic and mesotocinergic nerve fibres in the median eminence of the frog hypophysis (1979)
    Springer
    Cell & tissue research 204 (1979), S. 29-36 
    Details
    ISSN: 1432-0878
    Keywords: Median eminence ; Hypophysis ; Rana temporaria ; Vasotocinergic fibres ; Mesotocinergic fibres ; Immunocytochemistry ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary With the use of the unlabelled antibody peroxidase-antiperoxidase complex (PAP) technique at the electron microscopic level, it was shown that both the internal and the external regions of the median eminence of the frog contain separate vasotocinergic and mesotocinergic nerve fibres. This observation confirms the results of previous immunocytochemical studies at the light microscopic level. The mean size of the neurohypophysial hormone-containing granules in the external region of the median eminence is significantly smaller than that of the neurohypophysial hormone-containing granules in the internal region of the median eminence. No significant difference could be found between the mean granule size of the vasotocinergic and mesotocinergic fibres of either the internal or the external region of the frog median eminence.
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    URL: http://dx.doi.org/10.1007/BF00235162
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  • 19
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    Synaptic connections of the Nervus connectivus in the frontal ganglion of Periplaneta americana L. (Insecta) (1979)
    Springer
    Cell & tissue research 204 (1979), S. 155-159 
    Details
    ISSN: 1432-0878
    Keywords: Nervus connectivus ; Periplaneta ; Synaptic contacts ; Iontophoresis ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The course of the Nervus connectivus (N.c.), its branches, and synaptic connections within the frontal ganglion (FG) were investigated electron microscopically after cobalt iontophoresis of the N.c. The subsequent treatment of ultrathin sections with Timm's method was found to be very suitable for identifying the smallest branches. In the neuropil, fibers of the N.c. form Gray-I-type synapses, but also dyads are abundant, whereby the N.c. fibers occur exclusively in postsynaptic position with neurosecretory fibers. The possible role of these relationships is discussed.
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    URL: http://dx.doi.org/10.1007/BF00235172
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  • 20
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    The hypothalamo-hypophysial system of the lamprey, Lampetra fluviatilis L. (1979)
    Springer
    Cell & tissue research 204 (1979), S. 319-331 
    Details
    ISSN: 1432-0878
    Keywords: Median eminence ; Lamprey ; Regulation of pars distalis ; Fluorescence microscopy ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The proximal neurosecretory contact region (PNCR) of the lamprey, a homologue of the median eminence of tetrapods, was studied by light, fluorescence and electron microscopy. Paraldehyde fuchsin-positive neurosecretory fibers are seen mainly in the central part of the rostral subdivision of the PNCR. The Falck-Hillarp technique reveals a weak, mainly diffuse yellow-green fluorescence in the PNCR. The ultrastructure of the tanycyte layer of the PNCR is very similar to that in the neurohypophysis of the same species, although the funnel-shaped protrusions of the third ventricle in the rostral part of the PNCR are more frequent than in the neurohypophysis. Peptidergic A1 and A2 neurosecretory fibers are characterized by neurosecretory granules of 120– 200 nm and 100–150 nm in diameter, respectively. Monoaminergic B type fibers contain granules 80–100 nm in diameter. Neurosecretory terminals and the vascular endfeet of tanycytes make contact with the basement membrane of the avascular connective tissue layer separating the PNCR from the hypophysial pars distalis. It is suggested that both peptide and monoamine neurohormones diffuse through the thick connective tissue septa into the underlying blood vessels which supply the pars distalis and thus affect the function of its glandular cells.
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    URL: http://dx.doi.org/10.1007/BF00234643
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  • 21
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    Formation of sarcomeres in the embryonic heart of the lobster (1979)
    Springer
    Cell & tissue research 198 (1979), S. 477-486 
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    ISSN: 1432-0878
    Keywords: Embryonic heart ; Myogenesis ; Sarcomere ; Crustacea (Homarus americanus) ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Cardiomyoblasts in the myocardium of embryonic lobsters at 3–4 weeks and 6 months of development were examined with the transmission electron microscope in order to describe the events in the formation of sarcomeres in a neurogenic cardiac system. Thick and thin myofilaments appear first in the cell periphery near the sarcolemma. They align in parallel in a sequential fashion to form consecutive sarcomeric units. Well-defined A and I bands appear before any semblance of a Z line is present. The initial sarcomere is anchored to the sarcolemma by the insertion of thin myofilaments into a region of electron dense material associated intimately with the sarcolemma. Myofibrils grow outward in several planes away from the electron-dense regions of membrane that serve as focal points for myofibril formation.
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    URL: http://dx.doi.org/10.1007/BF00234192
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  • 22
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    The effect of L-DOPA on the ultrastructure of the adenohypophysis of the Chinese quail, Excalfactoria chinensis (1979)
    Springer
    Cell & tissue research 198 (1979), S. 521-526 
    Details
    ISSN: 1432-0878
    Keywords: Adenohypophysis ; Electron microscopy ; L-DOPA ; Lysosomes ; Chinese quail, Excalfactoria chinensis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Intraperitoneally injected L-DOPA was found to stimulate strongly the lysosomal system of all of the cell types of the adenohypophysis. We suggest that this amine may play a role in the regulation of the secretory activity of the gland by mediating the lysosomal activity, this role being of variable importance according to the fluctuations in hormonal activity. Ultrastructural changes occur in some cell types following injection of L-DOPA. The question as to whether these changes are induced directly by L-DOPA or via the monoaminergic system of the hypothalamus and its hypophysiotropic hormones is discussed.
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    URL: http://dx.doi.org/10.1007/BF00234195
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  • 23
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    Marginal bundles of axoplasmic microtubules at nodes of Ranvier within muscle (1979)
    Springer
    Cell & tissue research 199 (1979), S. 281-288 
    Details
    ISSN: 1432-0878
    Keywords: Annular microtubules ; Nodes of Ranvier ; Nerve ; Axon ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Using a special albumin technique, nodes of Ranvier have been examined within frog skeletal muscle, sciatic nerve and rat and frog cerebrum. Initial segments have been examined in cerebrum of frog and rat. Microtubules usually run longitudinally through these regions, but within the bare area of the intramuscular node of Ranvier, annular or helical bundles of microtubules run in a marginal band at right angles to the more centrally placed longitudinal microtubules. These nodal bare areas show a pronounced convexity and it is suggested that the annular microtubules serve to maintain this convexity during muscle contraction.
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    URL: http://dx.doi.org/10.1007/BF00236139
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    T-tubes in cultured mammalian myocardial cells (1979)
    Springer
    Cell & tissue research 203 (1979), S. 173-180 
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    ISSN: 1432-0878
    Keywords: Tissue culture ; Cardiac myocyte ; Heart ; T-tubes ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary T-tubes are among the last structural elements of the mammalian myocyte to develop in vivo. We were able to identify T-tubes in early cultures of neonatal rat myocytes. Ventricles were excised from 3- to 4-day-old neonatal rats, incubated overnight in cold trypsin, and treated with sequential changes of collagenase-hyaluronidase. Fractions of cells isolated in this manner were pooled and cultured in plastic petri dishes. In cells prepared for transmission electron microscopy, T-tubes were observed at the cell periphery of cultured myocytes, but were more difficult to identify as the cultures aged and became overgrown by fibroblasts. T-tubes were identified by virtue of their continuity with the sarcolemma, their relatively large diameter, and their regular entry at the level of the Z line. Even at optimal culture ages, T-tubes were not present in every myocyte. At the times T-tubes could be located, myocytes were beating and had begun to establish intercalated discs and gap junctions. The de novo formation of T-tubes in cultured myocytes of neonatal rat heart reflects a duplication of in vivo differentiation by the cultured myocyte. The appropriateness of cultured myocytes in the study of the development and physiology of the heart is emphasized by the in vitro formation of T-tubes.
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    URL: http://dx.doi.org/10.1007/BF00237231
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    The differentiation of monocytes into macrophages, epithelioid cells, and multinucleated giant cells in subcutaneous granulomas (1979)
    Springer
    Cell & tissue research 197 (1979), S. 355-378 
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    ISSN: 1432-0878
    Keywords: Monocytes ; Macrophages ; Epithelioid cells ; Multinucleated giant cells ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The morphological changes occurring in monocytes during their differentiation into macrophages, epithelioid cells, Langhans-type giant cells, and foreign-body-type giant cells were investigated in foreign-body granulomas induced by subcutaneous implantation of pieces of Melinex plastic. Analysis based on Adams's (1974) criteria for discrimination between the several types of cell of the monocyte line, showed that each type has a characteristic type of granule. Primary and secondary granules, numerous in the Golgi area of monocytes were generally found close to the cell membrane and decreased in number in maturing macrophages. This was accompanied by an increase in the number of microtubules. Mature macrophages show numerous characteristic macrophage granules, which are round (average diameter: 280 nm) and have a halo between the limiting membrane and granular matrix. Mature epithelioid cells have characteristic epithelioid cell granules, and multinucleated giant cells a heterogeneous population of granules. Fusing macrophages generally have their Golgi areas facing each other, and also show a reduced thickness of the cell coat. The morphology of the multinucleated giant cell is closely related to the number of nuclei present. In Langhans-type giant cells, which generally have two to ten nuclei, a giant centrosphere with numerous aggregated centrioles is found. In transition forms between Langhans-type and foreign-body-type giant cells, which generally contain 10–30 nuclei, the centrioles show less aggregation. In the foreign-body-type giant cells, which generally have more than 30 nuclei, centrioles are virtually absent and never aggregated. These differences between the Langhans-type giant cells, the foreign-body-type giant cells, and the transition forms, support our previous finding that Langhans-type giant cells are the precursors of foreign-body-type giant cells.
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    URL: http://dx.doi.org/10.1007/BF00233563
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    The androgenic effect on the fine structure of the harderian gland in the male hamster (1979)
    Springer
    Cell & tissue research 198 (1979), S. 119-127 
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    ISSN: 1432-0878
    Keywords: Male hamster ; Harderian gland ; Castration ; Sexual dimorphism ; Porphyrin ; Testosterone ; Tubular clusters ; Membranous structures ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary A sexual dimorphism of the hamster Harderian gland at the ultrastructural level has been reported. The effect of testosterone on the fine structure of the gland from castrated male golden hamsters is reported here. Harderian glands from the following three groups of animals were examined at regular intervals up to 60 days after castration: (1) castrated; (2) castratedsham-injected, receiving 0.1 ml sesame oil per day; (3) castrated-testosterone injected, receiving 2mg testosterone propionate in 0.1 ml sesame oil per day. In groups 1 and 2, clusters of cylindrical tubules, typical of the male gland, decreased in number and disappeared almost completely 2 weeks after castration. Membranous structures, typical of the female gland, prevailed in these two groups throughout the remaining period of experiment. On the other hand, these changes were prevented in the group of castrated animals maintained on testosterone propionate. It is concluded that castration modified the ultrastructure of the male hamster Harderian gland toward the female type and that daily administration of testosterone propionate prevented this change.
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    URL: http://dx.doi.org/10.1007/BF00234839
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    Distribution and fine structure of the lymphatic system in the human testis (1979)
    Springer
    Cell & tissue research 200 (1979), S. 15-27 
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    ISSN: 1432-0878
    Keywords: Lymph vessels ; Testis ; Man ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The distribution of lymph vessels in the human testis was investigated using ink injection methods, and light and electron microscopy. Lymph capillaries occur in the septula testis but are absent in the intertubular tissue. They consist of endothelial cells provided with an incomplete basal lamina and anchoring filaments of the adjacent connective tissue. Frequently, the endothelial cells are separated by gaps measuring up to 2μm. The lymph capillaries of the septula testis are connected to lymph vessels in the rete testis and tunica albuginea. These vessels have occasional smooth muscle cells and valves. At the posterior margin of the testis, the network of lymph vessels merges into collecting ducts, which together with vessels derived from the rete testis are drained by the lymphatic system in the spermatic cord.
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    URL: http://dx.doi.org/10.1007/BF00236883
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    The tanycyte of the rat median eminence (1979)
    Springer
    Cell & tissue research 200 (1979), S. 329-334 
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    ISSN: 1432-0878
    Keywords: Median eminence ; Axon terminals ; Tanycytes ; Electron microscopy ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The present ultrastructural study proves the existence of nerve terminals closely apposed to the plasmalemmata of tanycytes in the rat median eminence. Several of these “axo-tanycytic” endings display remarkable accumulations of agranular endoplasmic reticulum in the form of pleomorphic vesicles which are closely apposed on either side of the plasma membrane of each cell compartment. Some of these vesicular profiles give the impression of structural continuity across both membrane systems. This phenomenon is discussed in the context of being a potential substratum for communication between both cell compartments.
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    URL: http://dx.doi.org/10.1007/BF00236425
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    Are there specialized junctions in the pars maculata of the distal tubule? (1979)
    Springer
    Cell & tissue research 200 (1979), S. 337-344 
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    ISSN: 1432-0878
    Keywords: Glomerulo-tubular feedback ; Tight junctions ; Macula densa ; Distal tubule ; Electron microscopy ; Freeze fracture ; Horseradish peroxidase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In the present study the tight junctions at the macula densa were compared to those of the adjacent straight and convoluted segments of the distal tubule using freeze fracturing and thin sectioning techniques. Only insignificant differences were found in the number of strands and the apico-basal depth of the tight junctions in the three distal tubular segments of rat, dog and tree shrew. In experiments with horseradish peroxidase on mice and tree shrews, the tracer did not penetrate the apical junctions in any of the distal tubular segments. Our findings do not support the concept of considerably higher permeability of the tight junctions at the macula densa, as previously reported. Gap junctions were never observed in the distal nephron. The present results suggest that the glomerulo-tubular feedback is more likely to be mediated by transcellular resorption of solutes than by passive diffusion through a leaky paracellular shunt pathway.
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    URL: http://dx.doi.org/10.1007/BF00234846
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    Demonstration of acid phosphatase activity induced by 20-hydroxyecdysone in the fat body of Calliphora (1979)
    Springer
    Cell & tissue research 200 (1979), S. 435-442 
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    ISSN: 1432-0878
    Keywords: Fat body ; Calliphora ; Electron microscopy ; Cytochemistry ; Ecdysterone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In the larval fat body of Calliphora erythrocephala, protein accumulation and autophagic activity occur prior to the onset of puparium formation. The involvement of the lysosomal system in the degradation of sequestered protein and cell organelles can be demonstrated by the electron microscopical cytochemical localization of the lysosomal marker enzyme acid phosphatase in so-called protein granules. These granules contain not only newly synthetized or absorbed protein but also remnants of cell organelles such as mitochondria and endoplasmic reticulum. Ligation of the larvae behind the brain-ring gland complex prevents the appearance of these acid phosphatase positive granules. They can be induced in ligated larvae by the injection of 20 hydroxyecdysone into the abdomen. These findings are briefly discussed in relation to the role of moulting hormones in normal development, especially with regard to the induction of autophagic activity.
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    URL: http://dx.doi.org/10.1007/BF00234854
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    An electron microscopic study of lipid absorption in the pyloric caeca of rainbow trout (Salmo gairdnerii) fed wax ester — rich zooplankton (1979)
    Springer
    Cell & tissue research 200 (1979), S. 475-486 
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    ISSN: 1432-0878
    Keywords: Lipid absorption ; Pyloric caeca ; Electron microscopy ; Feeding experiment ; Rainbow trout
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Rainbow trout were killed 4 and 18 h after being fed wax ester-rich marine Zooplankton and the absorptive epithelium of the pyloric caeca examined by electron microscopy. Numerous osmiophilic drops were seen in the lamina propria underlying the epithelium of fish killed at both times, but these drops were only abundant within columnar epithelial cells of fish killed 4 h after feeding. Pinocytotic profiles were not common at the luminal plasma membranes, nor were osmiophilic droplets seen in the terminal web area between the luminal plasma membrane and the extensive smooth endoplasmic reticulum. Numerous osmiophilic droplets, 30–100 nm in diameter, were present in the cisternae of the smooth endoplasmic reticulum with up to five separate droplets per individual cisterna. Columnar epithelial cells also contained up to 100 large osmiophilic drops (“conglomerates”) which tended to be concentrated in the supranuclear (Golgi) regions. The conglomerates were 250–1200 nm in diameter and were themselves made up of smaller droplets 30–400 nm in diameter. Conglomerates were present both within intracellular membranes and free in the cytoplasm. Osmiophilic droplets in the intercellular spaces and lamina propria were similar in size to individual droplets within conglomerates. We conclude that triacylglycerols are elaborated in the smooth endoplasmic reticulum, transferred to and processed in the Golgi region and finally discharged serosally as chylomicron-like particles of not greater than 400 nm diameter.
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    Fine structure of the monkey epididymis: A correlated thin-section and freeze-cleave study (1979)
    Springer
    Cell & tissue research 201 (1979), S. 451-458 
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    ISSN: 1432-0878
    Keywords: Epididymis ; Freeze-fracture ; Electron microscopy ; Male reproduction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The epithelium of the monkey epididymis was studied by means of freeze-fracture techniques and conventional electron microscopy. For the study of transepithelial permeability lanthanum hydroxide was used as an intercellular tracer. The epididymal epithelium consists mainly of tall columnar cells. The long stereocilia at the apical surface, similarly to microvilli, exhibit after freeze-fracture, two distinct faces: the E face, concave and with fewer membrane-associated particles, and the complementary convex P face. In the lumen unusual groups of smooth-surfaced vacuoles are present. A tight junctional network, which shows some permeability to the lanthanum tracer, is located at the apical end of the cells. Supranuclear cross-fractures clearly show the well developed Golgi cisternae and numerous vacuole profiles. The highly infolded, centrally located nucleus exhibits, after freeze-fracture, an even distribution of nuclear pores. In the perinuclear region the rough endoplasmic reticulum, which also presents pores, displays a sheet-like organization. The basal cytoplasm is filled by numerous globular profiles of membrane-bounded granules. Freeze-cleave exposes large cytoplasmic areas where the types and amount of organelles indicate an intense metabolic activity.
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    URL: http://dx.doi.org/10.1007/BF00237003
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    A study of TSH-synthesis of spontaneously hypertensive rats by electron microscopic morphometry and autoradiography (1979)
    Springer
    Cell & tissue research 201 (1979), S. 467-477 
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    ISSN: 1432-0878
    Keywords: Anterior pituitary ; Hormone synthesis ; Morphometry ; Autoradiography ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In order to compare the functional state of the anterior pituitary of spontaneously hypertensive rats (SHR) with that of normotensive Wistar Kyoto rats (WKR), the anterior pituitary was examined by morphometry and autoradiography at the level of electron microscopy. The relative number and the relative volume of thyrotrophs in the anterior pituitary were significantly greater in SHR compared with age-matched WKR at 0, 7, 30–33 days, and 10 months of age, while the relative number of somatotrophs in SHR was significantly smaller at 1 and 10 months of age. Electron microscope autoradiographic analysis of uptake of 3H-lysine by thyrotrophs of both strains at the age of approximately one month showed that 3H-lysine was incorporated into protein and transported finally to secretory granules which migrated to near the cell membrane to be discharged. Silver grains were significantly more numerous over the thyrotrophs of SHR than over those of WKR at 30 min, 1 h, and 4h after the injection of 3H-lysine. The present study has ascertained morphologically that a congenital hypersynthesis of TSH by the anterior pituitary occurs in SHR.
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    Fine structure of isolated fibrils from the cuticle of Lumbricus sp. (1979)
    Springer
    Cell & tissue research 201 (1979), S. 459-466 
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    ISSN: 1432-0878
    Keywords: Electron microscopy ; Collagen ; Cuticle ; Lumbricus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary A method has been developed to isolate and purify cuticular fibrils of Lumbricus. Polarizing microscopy confirms the collagenous nature of the isolated fibrils. Study in the electron microscope of isolated fibrils, negatively or positively stained, shows that they are cylindrical, unbranching and without periodic structure. Enzymatic treatment of cuticles with alpha-amylase and trypsin results in a more or less complete dissociation of the fibrils which appear clearly to be made up of helically wound bundles of filaments (30–40 Å). The structure of the cuticular fibrils is discussed in relation to biochemical and biophysical data and compared to the ultrastructural organization of other periodically cross-banded fibrils.
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    URL: http://dx.doi.org/10.1007/BF00237004
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    Cell junctions in the cyst envelope in the silkworm testis, Bombyx mori linné (1979)
    Springer
    Cell & tissue research 202 (1979), S. 63-73 
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    ISSN: 1432-0878
    Keywords: Silkworm testis ; Cyst cell ; Junctions ; Freeze-fracture ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The cell junctions of the cyst envelope in the testes of Bombyx mori were examined by electron microscopy utilizing a thin-sectioning technique following conventional fixation, tannic acid fixation and lanthanum tracer study, and also using a freeze-fracture technique. There are three kinds of junctions; septate junctions, gap junctions and tight junctions. Septate junctions are of the pleated type. Gap junctions are characterized by four electron-dense lines and three electronlucent lines in the reduced intercellular spaces seen by thin-sectioning. They are of the “E” type, having clusters of intramembraneous particles on the E-fracture face. The most striking finding is the frequent presence of tight junctions on the fracture planes, while focally fused outer leaflets of the junctional unit membranes are rarely detected on thin-sectioned preparations. Tight junctions are characterized by branching zigzag ridges on the P-fracture face and complementary grooves on the E-fracture face. It is proposed that tight junctions are new morphological evidence of blood-germ cell barrier in an insect.
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    URL: http://dx.doi.org/10.1007/BF00239221
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    The fine structure of ventral prostatic secretory epithelial cells in older rats (1979)
    Springer
    Cell & tissue research 203 (1979), S. 181-188 
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    ISSN: 1432-0878
    Keywords: Ventral prostate ; Epithelial cells ; Electron microscopy ; Light microscopy ; Older rats
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ventral prostatic secretory epithelial cells in older rats were studied by light and electron microscopy. The cells vary in height in different parts of the same organ, and ultrastructurally they show the presence of a developed secretory apparatus such as well-developed Golgi body and abundant rough endoplasmic reticulum. They also show signs of a depressed secretory activity, involving occasional emiocytosis of apical secretory vacuoles and a paucity of condensing vacuoles in the Golgi region and above it. Further, they are characterized by the frequent occurrence of supra and paranuclear pleomorphic lysosomes.
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    Hybrid pigment organelles in an invertebrate (1979)
    Springer
    Cell & tissue research 196 (1979), S. 541-543 
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    ISSN: 1432-0878
    Keywords: Chromatophores ; Pigment organelles ; Organelle development ; Electron microscopy ; Phalangium opilio
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Observations of a number of vertebrate chromatophores have revealed the presence of more than one type of pigment organelles, suggesting that the different types are all derived from an equipotential organelle able to differentiate into any of the major pigment-containing organelles (Bagnara, 1972). Observations are presented concerning the occurrence of hybrid pigment inclusions, i.e., all kinds of intergrades between melanosomes, pterinosomes, and reflecting platelets in pigment cells of the daddy-long-legs. It therefore seems possible that pigment organelles in some invertebrates may also be derived from a common pluripotential primordial organelle.
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    URL: http://dx.doi.org/10.1007/BF00234747
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    Lysosomal breakdown of erythrocytes in the sheep placenta (1979)
    Springer
    Cell & tissue research 197 (1979), S. 79-94 
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    ISSN: 1432-0878
    Keywords: Erythrophagocytosis ; Lysosomes ; Placenta (sheep) ; Acid phosphatase ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The breakdown of erythrocytes within the lysosomal apparatus of trophoblastic epithelial cells of the sheep placenta was studied at the ultrastructural level. Acid phosphatase activity could be demonstrated in the interspace between the erythrocyte membrane and the lysosomal membrane, but not inside ingested erythrocytes. The erythrocyte plasma membrane remained observable until the final stage of the breakdown process. Together with a peripheral layer of indigestible hemoglobin it might form a barrier for further penetration of lysosomal enzymes into the ingested erythrocyte. The hemoglobin of the erythrocyte is suggested to diffuse through the erythrocyte plasma membrane into the interspace between this membrane and the lysosomal membrane. Subsequently, the hemoglobin is digested in the interspace or in fragments pinched off from erythrocyte-containing lysosomes (=erythrolysosomes). The fragmentation of erythrolysosomes is considered to be the most efficient mechanism for the breakdown of red blood cells in the trophoblastic epithelium of the sheep placenta. The method of entry of hydrolytic enzymes into erythrocyte-containing phagosomes is discussed.
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    Electron microscopy of the indoleamine-accumulating neurons in the retina of the rabbit (1979)
    Springer
    Cell & tissue research 197 (1979), S. 175-194 
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    ISSN: 1432-0878
    Keywords: Retina ; Synapses ; Transmitter ; Electron microscopy ; Rabbit
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The recently discovered indoleamine-accumulating retinal neurons were studied electron microscopically after destruction of the dopaminergic retinal neurons and subsequent labeling with 5,6-dihydroxytryptamine. These observations confirm earlier fluorescence microscopical studies on the distribution of the indoleamine-accumulating neurons in the rabbit retina. Their perikarya are known to be located in the inner nuclear layer (INL) among the amacrine cell bodies. Their processes are found only in the inner plexiform layer (IPL), most of them in the innermost third part of that layer. The indoleamine-accumulating terminals are pre- and postsynaptic to bipolar neurons in the innermost sublayer of the IPL. Reciprocal synapses are probably the rule. The synaptic vesicles of indoleamine-accumulating synapses onto bipolar cells are arranged in “globular” clusters around a central electron dense, round body. A number of synapses formed by unlabeled amacrine neurons with postsynaptic indoleamine-accumulating elements were also detected. These synapses were mainly found in the outermost third of the IPL. Synaptic contacts between presynaptic indoleamine-accumulating neurons and postsynaptic unlabeled processes of amacrine cells are very rare.
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    Fusion of erythrolysosomes in epithelial cells of the sheep placenta (1979)
    Springer
    Cell & tissue research 203 (1979), S. 209-221 
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    ISSN: 1432-0878
    Keywords: Erythrophagocytosis ; Lysosomes ; Placenta (sheep) ; Acid phosphatase ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In trophoblastic epithelial cells of the sheep placenta the breakdown of erythrocytes within complex erythrolysosomes was studied at the ultrastructural level. It was found that the formation of complex erythrolysosomes containing from two to several erythrocytes as a result of fusion of erythrolysosomes within the epithelial cells was a common occurrence when the epithelial cells engulfed a large number of erythrocytes. The erythrocytes enclosed in complex erythrolysosomes appear to be either in the same or in different stages of hemolysis. In the process of breakdown of erythrocytes within complex erythrolysosomes five successive stages of hemolysis could be distinguished. Acid phosphatase activity was demonstrated in the complex erythrolysosomes and appeared to be located in the angular interspaces between the erythrocytes and the lysosomal membrane. The fragmentation of complex erythrolysosomes with formation of small hemoglobin-containing lysosomes also occurred. The fusion of erythrolysosomes with formation of complex erythrolysosomes can be considered as an additional mechanism in the process of erythrocyte breakdown in the epithelial cells of the sheep placenta.
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    Transplantation experiments with the fat body of Calliphora: A morphometric study of induced ultrastructural changes (1979)
    Springer
    Cell & tissue research 203 (1979), S. 267-281 
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    ISSN: 1432-0878
    Keywords: Fat body ; Morphometry ; Metamorphosis ; Transplantation ; Calliphora ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Transplantation of fragments of the anterior fat body lobe of 4 day old feeding stage larvae into one day older hosts, which are at the end of feeding, leads to precocious induction of ultrastructural changes in the transplanted cells of the fat body. These changes include alterations in the mean relative and absolute areas of mitochondria, protein granules, lipid droplets and vacuoles. The extent of intracellular changes induced in the transplants depends on the physiological condition of the host. This confirms that alterations in the internal environment at termination of feeding induce premetamorphic changes in cells of the fat body.
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    Calcitonin-like cells in the pharynx of the ascidian Styela clava (1979)
    Springer
    Cell & tissue research 203 (1979), S. 301-309 
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    ISSN: 1432-0878
    Keywords: Endocrine cells ; Calcitonin ; Ascidian (Styela clava) ; Immunofluorescence ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary A small group of granulated endocrine cells have been described in the endostylar region of the pharynx in Styela. These cells are argyrophilic and exhibit calcitonin-like immunofluorescence. Tests with antisera to other peptides all proved negative. Cells from animals exposed to elevated calcium levels showed a degree of degranulation. The possibility that these cells may represent ancestral ultimobranchial “C” cells is discussed.
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    Ultrastructure and cytochemistry of the gastric mucosa of a reptile, Tiliqua scincoides (1979)
    Springer
    Cell & tissue research 197 (1979), S. 281-294 
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    ISSN: 1432-0878
    Keywords: Electron microscopy ; Light microscopy ; Gastric mucosa ; Reptilia ; Cytochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The gastric mucosa of a reptile, the lizard Tiliqua scincoides, has been examined by light and electron microscopy. The gastric pits lead into glands that are extensively coiled in the proximal stomach but become progressively shorter and straighter in the distal stomach. The following epithelial cell types have been identified: (i) Surface mucous cells (SMC) line the entire lumenal surface as well as the pits. They contain mucus granules that stain with periodic acid-Schiff and, like the granules of mammalian SMC, commonly contain an electron dense core that appears not to be mucus (periodic acid-chromic acid-silver methenamine nonreactive). (ii) Glandular mucous cells are present in glands throughout the mucosa. They are probably homologous with the mucous neck and antral gland cells of mammals; like SMC their mucus granules contain nonglycoprotein cores. (iii) Oxynticopeptic cells (OPC) are the predominant cell type in the proximal glands but become infrequent distally. Their fine structure resembles that of OPC in other nonmammalian vertebrates, with features like those of both parietal cells and zymogen cells of mammals, (iv) Endocrine cells of three different types have been identified. Two of these show close similarities to the EC and ECL cells of mammals.
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    Premetamorphic changes in the ultrastructure of Calliphora fat cells (1979)
    Springer
    Cell & tissue research 198 (1979), S. 79-93 
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    ISSN: 1432-0878
    Keywords: Fat body ; Calliphora ; Metamorphosis ; Morphometry ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In the fat body of Calliphora a drastic reorganization of the cell structure, which is related to premetamorphic functional changes, can be observed during the 3rd larval stage of development. These changes include an accumulation of protein storage granules, a decrease in the relative volume of the mitochondria and the surface area of endoplasmic reticulum membrane, and the disappearance of vacuoles. “Absolute” values obtained for organelle areas and membrane perimeters confirm the assumption that large numbers of organelles are eliminated by autophagic activity prior to the pupation period. A temporary restoration of the endoplasmic reticulum is found immediately before pupariation. Large variations in organelle density were found between individual fat cells and between the nuclear, mid- and peripheral regions of the cytoplasm.
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    Spatial distribution of excitatory innervation on a muscle fiber of the lobster (Homarus americanus) (1979)
    Springer
    Cell & tissue research 199 (1979), S. 171-175 
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    ISSN: 1432-0878
    Keywords: Crustaceans ; Neuromuscular synapse ; Multiterminal innervation ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The distribution of nerve terminals from a single excitatory motor axon has been followed along a fiber from the proximal accessory flexor muscle of the lobster by thin serial sectioning at periodic intervals. The excitatory motor axon provides small axonal branches (diameter 5–12 μm) of varying lengths that travel along the surface of the muscle fiber. Each of these branches gives rise to discrete synaptic terminals which are not uniformly distributed. Individual terminals vary in length from 10–60 μm and the majority possess neuromuscular synapses. The greatest distance between synapses is slightly over 1 mm which is well within the length constant (2.6 mm) of this muscle fiber. Thus the spatial distribution of synapses is such as to ensure adequate depolarization along the entire length of the muscle fiber.
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    URL: http://dx.doi.org/10.1007/BF00237737
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    Electron microscopic study of the giant cells in the olfactory bulb of labyrinth fish (Belontiidae, Perciformes) (1979)
    Springer
    Cell & tissue research 199 (1979), S. 509-517 
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    ISSN: 1432-0878
    Keywords: Olfactory bulb ; Giant cells ; Neurosecretion ; Electron microscopy ; Labyrinth fish
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The giant cells in the olfactory bulb of labyrinth fish, most likely belonging to the nervus terminalis, show ultrastructural features of active synthesis of secretory material. Dense core vesicles (70–100 nm in diameter), found in the perikaryon as well as in the axon, are the possible storage sites of the secretory substance. Its chemical nature is unknown. In some of these vesicles acid phosphatase is demonstrable. Large membrane-bound bodies (up to 2000 nm in diameter), either containing an electron dense matrix or debris of cytoplasmic organelles, are also acid phosphatase-positive, suggesting their lysosomal nature. Some other ultrastructural characteristics of these cells are also described.
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    On the problem of counting and sizing mitochondria: A general reappraisal based on ultrastructural studies of mammalian lymphocytes (1979)
    Springer
    Cell & tissue research 204 (1979), S. 297-303 
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    ISSN: 1432-0878
    Keywords: Mitochondria ; Electron microscopy ; Stereology ; Number and volume ; Lymphocytes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The authors ask the question whether the parameters “number” and “volume” are suitable for the morphometric analysis of mitochondria. In several types of cell, irregularity of mitochondrial shape makes it technically difficult, if not impossible, to obtain reliable stereological estimates of mean organelle volume or number per unit volume. Of more fundamental concern is whether number of mitochondria per cell is of any real value as a structural correlate of respiratory potential and hence as a measure of cell function. Alternative parameters might serve better for this purpose. Though the problem is illustrated by reference to quantitative studies of lymphocytes, it is also pertinent to the investigation of many other cell types.
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    URL: http://dx.doi.org/10.1007/BF00234641
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    A study of cells present in peripheral lymph of pigs with special reference to a type of cell resembling the langerhans cell (1979)
    Springer
    Cell & tissue research 202 (1979), S. 407-430 
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    ISSN: 1432-0878
    Keywords: Lymph (pig) ; Langerhans cells ; Phase contrast microscopy ; Histochemistry ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Large mononuclear cells with long, actively moving cytoplasmic veils were observed in lymph coming from the skin. The enzyme histochemistry and ultrastructure of these cells suggested that they are related to epidermal Langerhans cells and interdigitating cells in the lymph node. It has been reported that Langerhans cells and interdigitating cells play a role in contact hypersensitivity by taking up antigen and presenting it to thymus-dependent lymphocytes, and it is likely that the veiled cells in the lymph are also involved. After skin-painting with 1-fluoro-2,4-dinitrobenzene (DNFB), the veiled cells in lymph coming from the site of painting became more active and were observed contacting other cells present in the lymph; many large cellular aggregates were found. Since neutrophilic leucocytes and mononuclear phagocytes were the predominating cell types in this lymph, there was no evidence for a massive recruitment of immunocompetent lymphocytes at the site of painting. Neonatally thymectomized pigs do not develop allergic reactivity to DNFB. It is of interest that the number of veiled cells and their ability to form large cellular aggregates was not affected in these animals. Therefore, it is unlikely that the defect in responsiveness can be attributed to a failure in the function of veiled cells.
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    URL: http://dx.doi.org/10.1007/BF00220434
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    The fine structure of decalcified cartilage and bone: A comparison between decalcification procedures performed before and after embedding (1978)
    Springer
    Calcified tissue international 25 (1978), S. 179-190 
    Details
    ISSN: 1432-0827
    Keywords: Decalcification ; Electron microscopy ; Calcified matrices
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The ultrastructure of calcifying cartilage and bone has been examined under the electron microscope after using three different methods of decalcification. The first was carried out before embedding (by soaking specimens in EDTA or formic acid), the second after embedding (by floating ultrathin sections on formic acid), and the third after embedding (by soaking embedded specimens in EDTA or formic acid), and with later re-embedding. The first procedure invariably induces drastic changes in the fine structure of the cells and calcified matrix, probably as a results of the extraction of organic material along with extraction of mineral. The second and third procedures make it possible to preserve ultrastructural details perfectly in both cells and calcified matrix. Of the two, the third procedure is preferable because of its greater simplicity. In areas that are still calcifying, these post-embedding decalcification techniques reveal the presence of crystal-associated, filamentous organic structures which are not recognizable in specimens decalcified before embedding. These structures, which could have a key role in inducing and regulating crystal formation and growth, are less evident in fully calcified areas (but not at their borders). This may partly be due to the loss of glycan components in the matrix during calcification. The most important determinant, however, seems to be the fact that during calcification the components of the matrix, including collagen fibrils, are involved in an aggregation process which reduces the amounts of free chemical groups available for reaction with the stain solution. Because post-embedding decalcification does not disturb this state of aggregation, the stainability of the matrix and the electron microscopic evidence of its components remain very low.
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    URL: http://dx.doi.org/10.1007/BF02010766
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    Cellular calcium distribution in fetal bones studied with K-pyroantimonate (1978)
    Springer
    Calcified tissue international 26 (1978), S. 181-190 
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    ISSN: 1432-0827
    Keywords: Cellular calcium ; Electron microscopy ; Osteoblasts ; Chondrocytes ; Mineralization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The calcium distribution in cartilage and bone cells during beginning ossification of fetal mouse long bones was studied after fixation with 2% K-pyroantimonate in 1% osmium. In the developing periosteum, the future osteoblasts showed a sparse cation-antimonate precipitate over the cytoplasm. In young osteoblasts the precipitate was accumulated on the mitochondrial membranes and the plasmalemma. Both organelles were sharply outlined by precipitate in the mature osteoblasts at the onset of mineralization. X-Ray microprobe analysis of these organelles demonstrated the presence of both Sb and Ca. In the extracellular compartment, a collagen-associated precipitate with 50 to 60 nm periodicity appeared during osteoblastic differentiation. During the initial phase of matrix mineralization, a random gross precipitate appeared in the matrix and seemed to be accumulated by osmiophilic matrix vesicles while the collagen fibrils lost their precipitate. Subsequently, during the confluent phase of matrix mineralization, the precipitate rapidly disappeared from the cells, leaving them devoid of precipitate once they were surrounded by mineralized matrix. Similar changes were found in the chondrocytes of the growth plate, but cartilage collagen, unlike osteoid collagen, did not bind precipitate. The results indicate that both osteoblasts and calcifying cartilage cells bind calcium prior to matrix mineralization. Bone collagen has strong pyroantimonate binding capacity, but it is not directly involved with initial stages of matrix mineralization, which starts in close association with matrix vesicles.
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    Quantitative morphogenetic investigations on fine structural changes in the optic tectum of the rainbow trout (Salmo gairdneri) during ontogenesis (1978)
    Springer
    Development genes and evolution 184 (1978), S. 83-94 
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    ISSN: 1432-041X
    Keywords: Synaptogenesis ; Electron microscopy ; Visual acuity ; Fish development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The morphogenetic differentiation of synapses of the optic tectum of the rainbow trout was investigated at different stages of development (from hatching to adult) and compared with the improvement in visual discrimination (minimum separable). (1) The main phase of synaptogenesis (increase in number of synapses, length of contact zone and number of vesicles) begins about one week after hatching and continues up to the age of one month, when the larvae start swimming freely. (2) Myelination begins 26 days after hatching and induces the end of the synaptogenesis period. (3) The visual discrimination (minimum separable) of trout larvae improves from 30 degrees of arc on the 10th day after hatching to 1 degree on day 30, then to about 14 to 18 min of arc in the adult. The results are discussed with special reference to previous biochemical investigations on changes in the ganglioside composition of the trout brain during comparable periods of development.
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    X-ray diffraction and electron microscope study of osteons during calcification (1978)
    Springer
    Calcified tissue international 25 (1978), S. 133-143 
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    ISSN: 1432-0827
    Keywords: Osteon ; X-Ray diffraction ; Electron microscopy ; Calcification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary To obtain information on the changes in the inorganic bone fraction during calcification, low- and wide-angle X-ray diffraction techniques and electron microscopy have been applied to single osteon samples. The samples were cylindrically shaped and their axes corresponded to the axes of the Haversian canals. The selection was made according to the degree of calcification and the orientation of collagen bundles and inorganic particles. Osteons at both the initial and final stages of calcification were chosen. Arrangements of fiber bundles and inorganic particles in successive lamellae characteristic of three types of osteon were selected, that is, longitudinally structured osteons, transversely structured osteons, and alternately structured osteons. The results indicate that in osteonic lamellar bone there are two types of inorganic particles: (1) granules arranged in linear or needle-shaped entities with maximum width 40–45 Å, which are regularly distributed at the level of the main band of the collagen fibrils where their maximum length reaches the length of the main band itself; that is, about 400 Å; and (2) very long crystallites, with a diameter of 40–45 Å, which grow with their crystallographicc-axis parallel to the collagen fibrils and cover much more than a major collagen period.
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    The morphology of bone mineral crystals (1978)
    Springer
    Calcified tissue international 25 (1978), S. 217-222 
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    ISSN: 1432-0827
    Keywords: Bone mineral ; Electron microscopy ; X-ray diffraction ; Dark field
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Electron microscopical observations of the size and shape of bone mineral crystallites have not been in complete agreement with X-ray diffraction findings. The two prevalent viewpoints consider bone mineral crystals to be either rod, or plate like in habit. There appears to be agreement that the smallest dimension of the crystals is about 5 nm, but there is discrepancy in the reported c-axial lengths. The method of dark field imaging is used to obtain a quantitative measurement of the c-axial length distribution in rabbit, ox and human bone: mean c-axial lengths 32.6 nm, 36.2 nm and 32.4 nm, respectively, show no significant difference at the 5% level to the mean c-axial length measured by X-ray line broadening. Both bright and dark field images strongly suggest that bone mineral has a plate like form. Reasons for past discrepancies are discussed.
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    URL: http://dx.doi.org/10.1007/BF02010772
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    The crystal sheaths from bivalve hinge ligaments (1978)
    Springer
    Calcified tissue international 25 (1978), S. 45-51 
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    ISSN: 1432-0827
    Keywords: CaCO3 ; Amino acids ; Sheaths ; Ligament ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The aragonite crystals in the molluscan bivalve hinge ligament are surrounded by an organic sheath which is distinct from the remainder of the ligament matrix. Methods have been developed to isolate these sheathed crystals from the ligaments ofSpisula solidissima andMercenaria mercenaria employing a papain digestion of the matrix protein. The sheathed crystals fromSpisula have a CaCO3/protein ratio of 11.1 and those fromMercenaria a ratio of 29.6. The sheathed crystals and the empty crystal sheaths have been examined by electron microscopy for structural integrity. The sheath proteins exhibit much smaller proportions of the amino acids glycine and methionine than the hinge ligaments. These are characteristic amino acids of high concentration in the hinge ligaments of both species. The concentrations of acidic and basic amino acids are increased about two fold in the sheaths over those of the ligaments. Otherwise there is little similarity in the amino acid composition of the sheaths in the two species. However, SDS electrophoresis shows the sheaths of both to contain a major protein component with a molecular weight of about 25,000. The sheath protein from theMercenaria ligament contains about 5% carbohydrate and that ofSpisula sheaths less than 1% carbohydrate.
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    Characteristics of a cholera phage (1978)
    Springer
    Archives of microbiology 119 (1978), S. 303-304 
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    ISSN: 1432-072X
    Keywords: Vibrio cholera phage group II ; Properties ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The basic physical, chemical and physiological properties of a group II cholera phage belonging to Mukerjee's classification has been described.
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    Electron microscopy of the cell wall complex ofMethylomonas albus (1978)
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    Archives of microbiology 119 (1978), S. 227-229 
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    ISSN: 1432-072X
    Keywords: Cell wall ; Electron microscopy ; Methylomonas albus ; Goblet sub-units
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In surface view, the cell wall complex ofMethylomonas albus possesses a hexagonal pattern of ridges. Thin sections reveal a continuous layer of goblet-shaped elements attached to the outermost surface of the lipopolysaccharide membrane. A possible interpretation of the cell wall complex ofM. albus, based on the fine-structural data is presented.
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    Development and ultrastructure of the marine, parasitic oomycete, Lagenisma coscinodisci Drebes (Lagenidiales) (1978)
    Springer
    Archives of microbiology 116 (1978), S. 133-139 
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    ISSN: 1432-072X
    Keywords: Lagenisma ; Coscinodiscus ; Infection ; Endosymbiotic bacteria ; Tip growth ; Wall-less thallus ; Host-parasite interface ; Membranes ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Lagenisma coscinodisci is diplanetic and has two different cyst stages. The secondary cyst has a uniform cell wall of fibrillar material. It attaches to a Coscinodiscus frustule and germinates with an infection tube. The cyst becomes filled with an enlarging expulsion vacuole. The infection tube penetrates the diatom cell between the cingula. Inside the host cell the fungus grows as an irregularly branched wall-less thallus. In the hyphae apical vesicles are lacking. The infection tube is plugged by wall material. There are no microtubules which might participate in the morphogenesis of the thallus. The plasmalemma of the diatom is pushed inward but not pierced by the fungus. Along the host-parasite interface it lies closely paralled to the Lagenisma plasmalemma which is extremely straight here and measures about 10 nm instead of about 5–6 nm at the surfaces of other stages. The Coscinodiscus plasmalemma disintegrates at about the same time when the cytoplasm breaks down. The fungus allows bacteria to enter the diatom; there are also endosymbiontic bacteria in unattacked cells — The growth mechanisms are discussed and the host-parasite interface is compared with that of other fungi.
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    Isolation of lipopolysaccharides and the effect of Polymyxin B on the outer membrane of Corynebacterium autotrophicum (1978)
    Springer
    Archives of microbiology 118 (1978), S. 67-69 
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    ISSN: 1432-072X
    Keywords: Corynebacterium autotrophicum ; Outer Membrane ; Lipopolysaccharides ; Biochemical analysis ; Polymyxin B ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Lipopolysaccharides (LPS) from Corynebacterium autotrophicum were isolated and analyzed. Autotrophically grown cells contained 2–5 mg of partly purified LPS per g dry weight of lyophilized cells. Serological cross reaction with Lipid A antigen of Salmonella minnesota confirmed the presence of LPS in C. autotrophicum. Electron microscopy of negatively stained Polymyxin B-treated cells showed formation of blebs on the Outer Membrane indicating an interaction of Polymyxin B specifically with LPS. Up to now, no Gram-positive organisms are known which contain any LPS. Thus, C. autotrophicum, though giving opposite results when the Gram-staining reaction was applied by several authors, has to be classified into the group of Gram-negative bacteria.
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    Ultrastructure of carotenoid mutant strain R-26 of Rhodopseudomonas sphaeroides (1978)
    Springer
    Archives of microbiology 118 (1978), S. 305-308 
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    ISSN: 1432-072X
    Keywords: Carotenoid mutant strain R-26-Rhodopseudomonas sphaeroides ; Electron microscopy ; Intracellular membranes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Stained thin-sections and freeze-fractured preparations of the carotenoid-less mutant strain R-26 of Rhodopseudomonas sphaeroides grown photosynthetically revealed 2 morphological kinds of intracellular membrane systems- spherical vesicles distributed throughout the cytoplasm and lamellae confined to the periphery of the cell. The lamellar membranes appeared to be large, flattened vesicles.
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    Detection of small cryptic plasmids in Salmonella typhimurium strain LT2 (1978)
    Springer
    Archives of microbiology 119 (1978), S. 87-90 
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    ISSN: 1432-072X
    Keywords: Salmonella typhimurium strain LT2 (ColIb) ; Cryptic plasmids ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Small cryptic plasmids of molecular weights ranging from 1 to 3 Mdal were detected by electron microscopy in Salmonella typhimurium strain LT2 (ColIb). They were divided into different size classes. Two of the cryptic plasmids were transferred simultaneously with ColIb to Escherichia coli.
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    Fine structure and metabolic adaptation of red and white muscles in tuna (1978)
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    Environmental biology of fishes 3 (1978), S. 185-191 
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    ISSN: 1573-5133
    Keywords: Euthynnus affinis ; Electron microscopy ; Kawakawa tuna ; Red fibres ; White fibres ; Muscle size ; Activity ; Thermogenesis ; Thermal inertia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis An electron microscopic study of the red and white muscle fibres in the trunk musculature of the Kawakawa tuna (Euthynnus affinis) was carried out with a view to correlating their structure with metabolic adaptation. The red fibres which are considerably smaller in diameter (34.58 μm ± 6.16 S.D.) are characterized by their high content of myoglobin, mitochondria, lipid droplets and glycogen granules. The white fibres which are relatively larger in diameter (66.03 μm ± 11.59 S.D.) are characterized by their lack of myoglobin, low mitochondria) density, high content of glycogen granules and the conspicuous absence of lipid droplets. The characteristics in fine structure of the two fibre types are discussed in the light of their metabolic adaptation, the red fibres as being adapted for long term cruising movement utilizing lipid as the main source of energy and the white fibres for short bursts of activity metabolizing glycogen as the chief fuel. The tuna, with the acquisition of the counter-current heat exchange system which provides for the retention of the heat generated from high substrate oxidation in the red muscle and an efficient respiratory system, it is postulated, is well adapted for high speed sustained swimming.
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    Myosatellite cells associated with different muscle fibre types in the Atlantic hagfish (Myxine glutinosa, L.) (1978)
    Springer
    Cell & tissue research 195 (1978), S. 17-27 
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    ISSN: 1432-0878
    Keywords: Myosatellite cells ; Muscles ; Atlantic hagfish (Myxine glutinosa, L.) ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The incidence of myosatellite cells associated with “white” and “red” muscle fibres of the parietal muscle and “red” fibres of the craniovelar muscle was estimated by quantitative electron microscopy in the Atlantic hagfish (Myxine glutinosa, L.). Myosatellite cell nuclei constitute 3, 11 and 23 % of the total number of nuclei inside the basal lamina of the three types of muscle fibres, respectively. However, the total number of nuclei is highest in “white” fibres, most of the nuclei belonging to striated muscle cells. Myosatellite cell profiles in transverse sections constitute 23, 41 and 61 % of the number of muscle fibre profiles of the three types, respectively. The intervals between adjacent myosatellite cells are ∼ 135 μm in “white” fibres, ∼ 55 μm in “red” parietal fibres, and only ∼ 25 μm in craniovelar fibres. Since craniovelar fibres are also comparatively thin, myosatellite cells constitute a significant fraction of the volume inside the basal lamina in these fibres. The myosatellite cells are ∼ 30–50 μm long and up to 5 μm thick. Some myosatellite cells possess few organelles, whereas others appear to contain many free ribosomes, granular endoplasmic reticulum, prominent Golgi apparatus and lysosome-like bodies.
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    Ultrastructural localization of radiolabelled L-dopa in the endocrine hypothalamus of the rat (1978)
    Springer
    Cell & tissue research 195 (1978), S. 29-43 
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    ISSN: 1432-0878
    Keywords: Endocrine hypothalamus (rat) ; Arcuate nucleus ; L-dopa ; Autoradiography ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Light and electron microscopic autoradiography has been employed to define the neuroanatomical patterns of uptake and binding of radiolabelled L-dopa in the endocrine hypothalamus of the rat. A dorsomedial continuum of arcuate and periventricular neurons selectively sequester 3H L-dopa 20 min following its intraventricular infusion. By 40 and 60 min following the infusion labelling of neurons is minimal and supports the notion of rapid degradation. Other cell compartments such as tanycytes demonstrate uptake of 3H L-dopa. The ultrastructural localization and distribution of radiolabelled L-dopa (or its metabolites) in the rodent hypothalamus is discussed with respect to mechanisms and cell compartments involved in neuroendocrine regulatory processes.
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    Influence of maternal adrenalectomy on the ultrastructure of the adrenal gland in neonatal rats (1978)
    Springer
    Cell & tissue research 189 (1978), S. 277-286 
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    ISSN: 1432-0878
    Keywords: Maternal adrenalectomy ; Rat ; Influence on the adrenals of newborn animals ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Maternal adrenalectomy at 7 or 14 days of gestation produced increased cell necrosis within zona reticularis cells on the day of birth and at 24 or 48 h after birth. Small remnants or large portions of adrenocortical cells were present within macrophages. In otherwise normal adrenocortical cells, lipid droplets were incorporated within some mitochondria. Autophagocytosis of single mitochondria was observed within adrenocortical cells. Undoubtedly ultrastructural changes represent stimulation of adrenocortical cells in neonatal rats in response to maternal adrenalectomy.
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    URL: http://dx.doi.org/10.1007/BF00209277
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    A study of the fine structure of the pit organ of the common Japanese sea eel Conger myriaster (1978)
    Springer
    Cell & tissue research 189 (1978), S. 375-388 
    Details
    ISSN: 1432-0878
    Keywords: Lateral line organ ; Pit organ ; Sea eel (Conger myriaster) ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The fine structure of the pit organ of the sea eel has been studied by means of electron microscopy. The sensory epithelium of the pit organ consists of sensory cells and supporting cells. The apical surface of the sensory cell is studded with sensory hairs consisting of a kinocilium and stereocilia. The sensory cells are divided into two groups. In one, the kinocilium points dorsally and in the other the kinocilium points ventrally. The total number of sensory cells in one pit organ is about 100, and the ratio of cells with opposite polarity is about 1∶1. On the basis of these structural features, the pit organ is considered to be a mechano-receptor sensitive to the movement of liquid in a dorso-ventral direction. It may also serve as an ion receptor, sensitive to environmental ion concentration. Efferent nerve terminals make rare synaptic contacts on the afferent nerve fiber.
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    URL: http://dx.doi.org/10.1007/BF00209127
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    On T-tubule openings at the sarcolemma of white fast-twitch muscle fibres in fish and frog (1978)
    Springer
    Cell & tissue research 188 (1978), S. 265-272 
    Details
    ISSN: 1432-0878
    Keywords: Muscles ; T-system ; Fish ; Frog ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In “white” muscle fibres of a teleost fish T-tubule openings may occur regularly at all Z-disc levels between adjacent peripheral myofibrils, the T-tubule openings thus occurring at a density of ca. 0.9 μm-2. In frog “white” fibres, T-tubule openings are infrequently seen in material fixed like the fish material. In material prepared according to the albumin method of Gray (1975, 1976 a, b) which renders the muscle fibres swollen, straight tubules or sometimes chains of vesicles instead are seen opening at the sarcolemmal surface. Such tubules occur at a higher density than expected from experiments with local activation of contraction. Lability and dynamics within the T-system normally and during fixation are discussed.
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    URL: http://dx.doi.org/10.1007/BF00222636
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    Penetration of spermatozoon into the ovum and transformation of the sperm nucleus into the male pronucleus in the domestic fowl, Gallus gallus (1978)
    Springer
    Cell & tissue research 190 (1978), S. 89-98 
    Details
    ISSN: 1432-0878
    Keywords: Fertilization ; Membrane fusion ; Male pronucleus ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The apex of the sperm head which has undergone the acrosome reaction comes in contact with the plasma membrane of the ovum. After the entire surface of the inner acrosomal membrane has come into close contact with the plasma membrane of the ovum, the two membranes fuse to form a continuous membrane. All parts of the spermatozoon that are devoid of plasma membrane penetrate into the ooplasm. As the head of the spermatozoon moves deeper into the ooplasm, the chromatin begins to disperse, and the head of spermatozoon is transformed into a large spherical nucleus with low electron density. At a later stage of the transformation, many small vesicles appear around the nucleus and subsequently fuse to form two continuous membranes. These membranes represent the male pronuclear envelope. The condensation of the chromatin occurs in places in the nucleus, so that the male pronucleus is formed. During the course of the formation of the male pronucleus, the subacrosomal rod and tail become detached from the head and disintegrate.
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    URL: http://dx.doi.org/10.1007/BF00210039
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    Gonadotropic cells in the Atlantic salmon, Salmo salar (1978)
    Springer
    Cell & tissue research 191 (1978), S. 187-203 
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    ISSN: 1432-0878
    Keywords: Pituitary ; GTH-cells ; Teleost ; Immunofluorescence ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The gonadotropin-producing cells (GTH-cells) in the Atlantic salmon were studied light and electron microscopically before, during and after spawning, and after injections of luteinizing hormone-releasing hormone (LH-RH). The double immunofluorescent technique was applied using rabbit anti-carp GTH as the first antibody. Numerous immunofluorescent cells were observed throughout the pars distalis, but very few in the pars intermedia. These cells are basophilic and PAS-positive, and ultrastructurally classified as globular gonadotropes. Only one gonadotropic cell type could be identified; its size, morphology and fine structure vary considerably. In the same specimen the GTH-cells can be predominantly globular or vesicular in appearance, depending on the reproductive phase of the fish. At spawning and after LH-RH injection, many GTH-cells reach a vacuolar stage; the content of the vacuoles is not immunofluorescent. Another cell type, which resembles GTH-cells in semithin sections, did not show gonadotropic properties; its nature and functional significance are unknown. In addition, the present study revealed an increase in the synthetic and exocytotic activity of prolactin cells after LH-RH injections. It is suggested that LH-RH mediates this effect via LH and eventually via estradiol.
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    URL: http://dx.doi.org/10.1007/BF00222419
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    Studies on the ultrastructure of the integument of the rotifer Habrotrocha rosa Donner (Aschelminthes) (1978)
    Springer
    Cell & tissue research 189 (1978), S. 167-177 
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    ISSN: 1432-0878
    Keywords: Hypodermis ; Rotifer ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The integument of the rotifer Habrotrocha rosa Donner is provided with pores and formed by an extrasyncytial cuticle and a syncytial hypodermis. The hypodermis peripherally contains 3 layers of dense cytoplasm and borders the cuticle by an asymmetric cell membrane. The wall of the pores is stiffened proximally like an annulus. The pores lead into cytoplasmic invaginations which are surrounded by vesicles. Close to and also beneath the condensed cytoplasmic layers microbodies are found, which are interpreted as microperoxisomes. Subhypodermal layers of muscles are connected with the cytoplasm of the hypodermis by desmosome-like structures.
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    URL: http://dx.doi.org/10.1007/BF00223127
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    Endocrine cells in the gut of the ascidian Styela clava (1978)
    Springer
    Cell & tissue research 187 (1978), S. 159-165 
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    ISSN: 1432-0878
    Keywords: Endocrine cells ; Ascidian (Styela clava) ; Gut epithelium ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Ultrastructural studies have shown the presence of two types of granulated endocrine cell in the gut of Styela clava. Type I, which occurs in the stomach and intestine contains small irregular granules, each with a distinct halo. Type II, found only in the oesophagus contains larger rounded granules, often with little or no halo. The characteristics of these two cell types are compared with those of endocrine cells found in the digestive tracts of other protochordates and discussed with special reference to the evolution of gastrointestinal endocrine cells in vertebrates.
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    URL: http://dx.doi.org/10.1007/BF00220628
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    Nerve-purkinje fiber relationship in the moderator band of bovine and caprine heart (1978)
    Springer
    Cell & tissue research 188 (1978), S. 11-18 
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    ISSN: 1432-0878
    Keywords: Purkinje fibers (Ox, goat) ; Axons ; Nerve endings ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The moderator band in the heart of the ox and goat contains bundles of Purkinje fibers and nerve fibers separated by connective tissue. The axons are mostly unmyelinated and embedded in the cytoplasm of Schwann cells. Small bundles of axons run close to the Purkinje fibers. The axons dilate into varicosities 0.5 to 1.6 μ in diameter (mean 0.95 μ), containing three types of vesicles: 1) agranular vesicles with a diameter of 400–500 Å, 2) large dense-cored vesicles with a diameter of 800–1200 Å, 3) small dense-cored vesicles with a diameter of 500 Å. Most varicosities contain agranular vesicles together with a few large dense-cored vesicles. The gap between the varicosities and the nearest Purkinje fiber is unusually wide and normally varies between 0.3 μ and 0.8 μ. No intimate nerve-Purkinje fiber contacts, with a cleft of 200 Å, were observed.
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    URL: http://dx.doi.org/10.1007/BF00220511
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    Local degenerative changes in the drum muscles of piranhas (Serrasalminae, Characidae) (1978)
    Springer
    Cell & tissue research 188 (1978), S. 75-82 
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    ISSN: 1432-0878
    Keywords: Drum muscles ; Piranha ; Degenerative changes ; Fine structure ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In the posterior drum muscle of the piranha structural alterations are frequently observed. Electron microscopic studies revealed a disordering of the myofibrils in these regions, accompanied by conspicuous changes in the mitochondria. As the degree of disorder increases, the mitochondrial cristae initially swell to form vesicles. Eventually the mitochondria become filled with myelin-like lamellar structures, which in many cases coalesce to form a dense outer wall. A striking concentration of lysosomes into localized masses was also characteristic of these regions.
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    URL: http://dx.doi.org/10.1007/BF00220515
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    The passage of spermatozoa through the vitelline membrane in the domestic fowl, Gallus gallus (1978)
    Springer
    Cell & tissue research 188 (1978), S. 497-508 
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    ISSN: 1432-0878
    Keywords: Fertilization ; Domestic fowl ; Acrosome reaction ; Vitelline membrane ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The developing outer layer of the vitelline membrane of the ovum in the posterior part of the infundibulum of the domestic fowl contains many spermatozoa in nearly parallel orientation with its inner layer. When the acrosomal region of a spermatozoon approaches or contacts the inner layer, promptly undergoes the acrosome reaction. The outer acrosomal membrane and overlying plasma membrane fuse together and the apical region of the acrosome opens, so that the acrosomal contents are released. Meanwhile the spermatozoon remains a time in contact with the surface of the inner layer, and the network of the inner layer just under the tip of the sperm head begins to be dissolved. This dissolution extends downward forming a tunnel, approximately 9 μm in diameter. The spermatozoon then passes through the inner layer obliquely via the central region of the tunnel and arrives at the perivitelline space.
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    URL: http://dx.doi.org/10.1007/BF00219787
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    Effects of systemic administration of 6-hydroxydopamine on the circumventricular organs in nonhuman primates (1978)
    Springer
    Cell & tissue research 191 (1978), S. 141-150 
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    ISSN: 1432-0878
    Keywords: Subfornical organ ; Third ventricle ; 6-Hydroxydopamine ; Electron microscopy ; Primate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The neurotoxin 6-hydroxydopamine (6-OH-DA) has been shown to produces degenerative changes in noradrenergic nerve terminals and preterminals in the CNS following intracisternal, intraventricular, and stereotaxic injection into the brain parenchyma. Systemic injections of this drug are also known to result in degenerative changes in noradrenergic terminals in the peripheral nervous system and in the circumventricular organs (CVO; areas of the CNS which lie outside the blood brain barrier). In the present study eight adult female cynomolgus monkeys were employed. The four experimental animals were injected on two successive days with 150 and 200 mg/kg 6-OH-DA, respectively. The four controls received only the diluent consisting of 0.1% ascorbic acid in normal saline. Two animals from each of the experimental and control groups were sacrificed at 2 h and 24 h after the second injection. Degenerative changes in the SFO neurons were characterized by a generalized increase in electron density of cytoplasmic elements in axonal terminals and preterminals. Multilamellar bodies, and increases in the number of dense core vesicles, dense bodies and secondary lysosomes were also observed after treatment with 6-OH-DA. The neurons showed clumping of mitochondria, which also appeared to be undergoing degenerative changes. The vacuoles in some supraependymal cells were greatly dilated as was the Golgi apparatus in the ependymal cells. The ependymal cell layer appeared to be intact, but there were areas immediately deep to this cell layer that contained large extracellular spaces. This increase in extracellular space was also commonly observed surrounding the perivascular spaces. These phenomena greatly contribute to the “spongy” appearance that the SFO takes on after 6-OH-DA administration.
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    URL: http://dx.doi.org/10.1007/BF00223222
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    The frontal ganglion of Periplaneta americana L. (insecta) (1978)
    Springer
    Cell & tissue research 191 (1978), S. 171-182 
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    ISSN: 1432-0878
    Keywords: Frontal ganglion ; Periplaneta ; Synaptic contacts ; Immunohistochemistry ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The frontal ganglion, part of the stomatogastric nervous system, contains about 60 to 80 neurons, 25 to 30 μm in diameter. A well developed Golgi system, producing dense-core vesicles, lysosomes, multivesicular bodies and dense bodies are abundant. Glia elements are sparsely distributed. Many nerve fibres contain granules of different size and electron density. Five groups of fibres can be distinguished: Fibres with granules of about 200 nm (type A), fibres with granules of about 160 to 170 nm (type B), fibres with granules of about 80 to 100 nm (type C) and those with synaptic vesicles of 50 nm (type D) respectively. A fifth very small type contains neither vesicles nor granules. Special attention was paid to synaptic contacts. The divergent dyad seems to be the main type in the frontal ganglion. Frequently, neurosecretory endings are observed in presynaptic position. Immunocytochemical “staining” of neurosecretory material closely corresponds to the distribution of type A fibres, as observed electron microscopically. Immunoelectrophoresis of extracts from frontal ganglia with polyspecific anti-neurosecretion-serum reveals a single precipitation line, indicating that the immunocytochemical localization of neurosecretory material is due to reaction with a specific as well as a crossreagent antibody.
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    URL: http://dx.doi.org/10.1007/BF00223225
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    Crystalloid structures within giant mitochondria of the prothoracic glands of Spodoptera littoralis (Bois) (Lepidoptera) (1978)
    Springer
    Cell & tissue research 191 (1978), S. 357-362 
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    ISSN: 1432-0878
    Keywords: Prothoracic glands ; Insects ; Electron microscopy ; Macromitochondria ; Crystalloid organization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The fine structure of the prothoracic glands of Spodoptera littoralis was investigated during the first half of the last larval instar. The secretory cells have two types of mitochondria, micromitochondria and macromitochondria. The micromitochondria have rounded to elongated profiles and sometimes branch. They contain lamellar, tubular and also tubulo-vesicular cristae. The macromitochondria appear generally rounded or oval and possess tubular cristae. Many regular parallel membranes appear within macromitochondria. Favorable sections show tubular structures packed in honeycomb fashion. The mitochondrial cristae are in connection with the tubular structures. Honeycomb and parallel membranes increase in number as the size of the macromitochondria increases.
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    URL: http://dx.doi.org/10.1007/BF00222430
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    Effects of antimicrotubular agents on the fine structure of the Golgi complex in embryonic chick osteoblasts (1978)
    Springer
    Cell & tissue research 193 (1978), S. 247-257 
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    ISSN: 1432-0878
    Keywords: Osteoblasts (Chick embryo) ; Golgi complex ; Microtubules ; Colchicine ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Embryonic chick frontal bones were cultured in the presence of colchicine or vinblastine and subsequently examined by transmission electron microscopy. In control cultures the osteoblasts showed a large Golgi complex consisting of dictyosomes arranged in a well-defined juxtanuclear area. Microtubules were particularly numerous within this Golgi area although they could be observed throughout the cytoplasm. Colchicine and vinblastine caused the disappearance of cytoplasmic microtubules, while bundles of 10nm diameter filaments appeared more frequently. In addition, cell polarity was lost and the Golgi complex became disorganized, with the dictyosomes randomly dispersed in the cytoplasm and showing a decreased number of cisternae and an increased number of vacuoles, the latter generally lacking stainable material. Increased number of autophagosomes were also noted. These findings indicate that microtubules function in the organization of the Golgi complex in osteoblasts. In view of the well documented role of this organelle system in collagen secretion it is suggested that previously observed secretory disturbances produced by antimicrotubular drugs may be due to a defective transfer of material to the dictyosomes and/or a defect in the packaging and transport of such material away from them.
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    URL: http://dx.doi.org/10.1007/BF00209038
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    Recent observations on the ultrastructure of human urothelium (1978)
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    Cell & tissue research 193 (1978), S. 543-560 
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    ISSN: 1432-0878
    Keywords: Human ; Urinary bladder epithelium ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary An electron microscopic study of normal bladder urothelium of elderly patients ranging in age from 61 to 82 years has shown the occurrence of unusually thin regions consisting of either one or two layers of undifferentiated cells interspersed between 3–4 cell layers thick regions. A morphometric study has confirmed the existence of a pattern of cytodifferentiation in cells of the thick region. The generally microvillous nature of the luminal surface is attributed to incompletely differentiated cells that have come to occupy the superficial layer. The lack of thickened and/or asymmetric membrane plaques in luminal plasma as well as the dearth of characteristic precursor vesicles in the cytoplasm are also explicable in terms of a failure of normal cell differentiation. It is suggested that the unusual features noted are consequences of tissue ageing rather than prognostic of cancer. There are indications that the aged urothelium may be prone to increased leakiness and the bladder tissues may therefore be at greater risk from urine-borne chemicals and carcinogens.
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    URL: http://dx.doi.org/10.1007/BF00225350
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    Ultrastructural and cytochemical studies on the cytodifferentiation of duodenal endocrine cells (1978)
    Springer
    Cell & tissue research 194 (1978), S. 79-102 
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    ISSN: 1432-0878
    Keywords: Duodenum ; Endocrine cells ; Differentiation ; Immunocytochemistry ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The development and cytodifferentiation of endocrine cells that produce the gastrointestinal hormones gastrin, cholecystokinin and secretin have been studied by a combined fluorescence-cytochemical, immunocytochemical and ultrastructural approach. The results show that, during development, several ultrastructurally distinct cell types exhibit COOH-terminal gastrin and cholecystokinin immunoreactivity. Furthermore, some cells simultaneously contain both gastrin- and cholecystokinin-specific antigenic determinants. Studies on the time course of development of gastrin and cholecystokinin cells, together with the above-mentioned data, suggest that gastrin cells may be converted into cholecystokinin cells in development. During this period, gastrin, cholecystokinin and secretin cells store the biogenic monoamine, 5-hydroxytryptamine a feature not displayed by the adult counter-parts of these cells. In the adult duodenum, characteristic enterochromaffin (EC) cells store 5-hydroxytryptamin for which, evidence for a possible hormonal role has been presented. Taken together, our data indicate that the differentiation of duodenal endocrine cells occurs in distinct steps, each involving a restriction in the biosynthetic repertoire of the cell.
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    Cytochalasin B-induced changes in concanavalin A-activated lymphocytes (1978)
    Springer
    Cell & tissue research 194 (1978), S. 279-285 
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    ISSN: 1432-0878
    Keywords: 14C-thymidine incorporation ; Autoradiography ; Multinucleated blasts ; Electron microscopy ; Deformities of cellular membranes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Cytochalasin B (CB) administered simultaneously with a mitogenic dose of concanavalin A (Con A) interferes with the activation process. This interference involves structural alterations of cellular membrane which do not include a reduced Con A-binding capacity. This conclusion is supported by the observation of deformities in both nuclear and cytoplasmic membranes in Con A-activated lymphocytes subsequently treated with CB. The high incidence of membrane blebs and pseudomyelin bodies in the cytoplasm points to a general effect of CB on the structural organization of membrane which may secondarily interfere with some specific event such as generation or transfer of signals for activation or cytokinesis.
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    URL: http://dx.doi.org/10.1007/BF00220394
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    Chrysosphaerella (Pseudochrysosphaerella)solitaria, spec. nova (Chrysophyceae) (1978)
    Springer
    Plant systematics and evolution 129 (1978), S. 135-142 
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    ISSN: 1615-6110
    Keywords: Algae ; Chrysophyceae ; Chrysosphaerella solitaria ; Electron microscopy ; phytoplankton
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A new unicellular species of the genusChrysosphaerella (Chrysophyceae) was found in fresh-water ponds in Switzerland, Japan, and the U.S.A. It is described asC. solitaria. The genus is divided into two subgenera:Chrysosphaerella, comprising the colonial species, andPseudochrysosphaerella, the unicellular ones.
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    URL: http://dx.doi.org/10.1007/BF00988987
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    Presynaptic and postsynaptic organelles of synapses formed in cultures of previously dissociated mouse spinal cord (1978)
    Springer
    Cell & tissue research 194 (1978), S. 503-511 
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    ISSN: 1432-0878
    Keywords: Cell cultures ; Electron microscopy ; Synaptic organelles ; Spinal cord (mouse)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary This study describes some of the ultrastructural features of presynaptic and postsynaptic organelles at synapses developed in cultures of previously dissociated mouse spinal cord cells. Particular attention was paid to the agranular reticulum which is well developed at many presynaptic and postsynaptic sites, either in the form of simple tubules or cisternae, or more complex networks and often closely associated with mitochondria. In addition, the disposition of microtubules at and close to synaptic specializations is described. These and other features of synaptic zones, such as granular vesicles in presynaptic sites, are discussed in relation to cultures developed on feeder layers and synapses in vivo, and in relations to possible degenerative and regenerative events in the cell cultures.
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    URL: http://dx.doi.org/10.1007/BF00236169
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    Ultrastructural evidence for adrenergic nerve degeneration in the guinea pig uterus during pregnancy (1978)
    Springer
    Cell & tissue research 195 (1978), S. 189-193 
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    ISSN: 1432-0878
    Keywords: Guinea pig uterus ; Myometrium, pregnancy ; Sympathetic nerves ; Electron microscopy ; Axon degeneration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In the guinea pig myometrium, the adrenergic nerves selectively demonstrated at the ultrastructural level after treatment with 5-OH-DA, show varying degree of degeneration during pregnancy. The changes are more extensive in a late gestational stage (40–45 days) than in an early one (20–25 days), and are particularly evident in the uterus overlying the conceptus as compared to the regions between the fetuses. Scattered degenerative changes were also observed in myometrial specimens from virgin animals, but probably reflect the normal continuous turnover of axons.
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    URL: http://dx.doi.org/10.1007/BF00233686
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    The effects of vinblastine on acinar cells of the exorbital lacrimal gland of the rat (1978)
    Springer
    Cell & tissue research 195 (1978), S. 227-237 
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    ISSN: 1432-0878
    Keywords: Vinblastine ; Lacrimal gland ; Electron microscopy ; Autophagy ; Secretion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The effects of vinblastine treatment on acinar cells of the rat exorbital lacrimal gland were studied by electron microscopy. Experimental animals of both sexes were given single intraperitoneal injections of (1) vinblastine (4mg/kg body weight) at 1 to 24 h before sacrifice; (2) pilocarpine (20 mg/kg b.w.) for 1 h; or (3) vinblastine for l h followed by pilocarpine for 1 h. Vinblastine treatment caused a number of changes including autophagocytosis, formation of intracisternal granules, and alteration of secretory granules. These changes varied in extent and onset between male and female rats. In addition, the Golgi apparatus was reduced in size and dispersed throughout the cytoplasm. Mitotic figures were commonly observed. Moreover, vinblastine inhibited the pilocarpine-stimulated degranulation of the acinar cells. In view of the known anti-microtubular action of vinblastine, these results suggest that microtubules are involved in various aspects of the transport, packaging, and secretion of exportable proteins in the lacrimal gland. Additionally, autophagocytosis and alteration of secretory granules may partially result from the interaction of vinblastine with membranes.
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    URL: http://dx.doi.org/10.1007/BF00236721
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    Non-ependymal cilia in the habenulae and the interpeduncular nucleus of the frog tadpole (1978)
    Springer
    Cell & tissue research 195 (1978), S. 527-533 
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    ISSN: 1432-0878
    Keywords: Ciliated neurons ; Habenula ; Interpeduncular nucleus ; Electron microscopy ; Rana esculenta, tadpole
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Cilia of the 9+2 pattern are found electron microscopically in nonependymal cells of the habenulae and the interpeduncular nucleus of the tadpole of Rana esculenta at an early stage of development (8 mm length, head to tip of tail). A comparison is made between these and the ependymal and sensory cilia in the same specimens. The cilia project into the neuropil emerging from a perikaryon rich in free ribosomes and displaying a prominent Golgi apparatus. These perikarya contain dense core vesicles. Synapses with vesicles of the clear spherical type have been observed along the ciliary shaft. On a purely morphologic basis the authors hypothesize that these cilia, at least in this early ontogenetic stage, may extend considerably the conducting surface of the cell and represent a sensory structure which could be stimulated by terminal processes belonging to distantly located cells. In addition, they could also be involved in the trophic exchange of material with the adjacent structures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00233894
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  • 86
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    Phagocytosis of osteocytes by osteoclasts in femora of two week-old rabbits (1978)
    Springer
    Cell & tissue research 195 (1978), S. 557-564 
    Details
    ISSN: 1432-0878
    Keywords: Osteoclasts ; Osteocytes ; Bone resorption ; Phagocytosis ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The osteoclast-osteocyte relationship at the endosteal surface of femora of two-week old rabbits was studied. Light microscopic observations suggest that during physiological resorption phagocytosis by osteoclasts of osteocytes takes place. Serial sections confirm that the cells are totally engulfed within the cytoplasm of the osteoclasts. Ultrastructural studies support these findings and indicate that the initial stage of phagocytosis of the osteocytes consists of the insinuation of an extension of the ruffled border into the osteocyte lacuna. These extensions are seen to make close contact with the osteocytes prior to their engulfment by the osteoclasts and their final digestion within phagosomes.
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    URL: http://dx.doi.org/10.1007/BF00233897
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  • 87
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    Catecholaminergic innervation of muscles in the hindgut of crustaceans (1978)
    Springer
    Cell & tissue research 189 (1978), S. 257-266 
    Details
    ISSN: 1432-0878
    Keywords: Neuromuscular junction ; Hindgut ; Crustacea ; Catecholamine ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The crustacean species Pacifastacus leniusculus and Gammarus pulex were investigated by electron microscopy in a search for possible neuromuscular junctions in the hindgut, which has a rich supply of catecholaminergic fibres. True neuromuscular synapses were found in both species between nerve terminals containing dense-core vesicles (80–110 nm in diam.) and muscle fibres. We suggest that the dense-core vesicle terminals contain a catecholamine, and this is supported by ultrahistochemical tests for monoamines. Two types of junctions are found: one in which the nerve terminal is embedded in the muscle cell (both species) and one in which protrusions from the muscle cell meet nerve terminals (Pacifastacus). Gammarus pulex, which has only circular muscles in the hindgut, has only catecholaminergic innervation, whereas Pacifastacus leniusculus has circular and longitudinal muscles both with at least two types of innervation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00209275
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  • 88
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    Parenchymal fine structure of the subfornical organ in the Japanese quail, Coturnix coturnix japonica (1978)
    Springer
    Cell & tissue research 191 (1978), S. 405-419 
    Details
    ISSN: 1432-0878
    Keywords: Subfornical organ ; Japanese quail, Coturnix coturnix japonica ; Monoaminergic innervation ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The parenchyma of the subfornical organ (SFO) of the Japanese quail was studied by light and electron microscopy. The SFO consists of ependymal, intermediate, and basal (perimeningeal) layers. In the intermediate layer, neurons, glial cells, and their processes are found. Axons containing dense core granules approximately 80 nm in diameter are numerous, some of which make synaptic contact with the neuronal perikarya or dendrites. Synaptic vesicles in some axons contain a dense dot in the interior after treatment with 5-hydroxydopamine. The activity of the SFO, which is probably concerned with elicitation of drinking by angiotensin II, may be regulated at least partly by afferent monoaminergic axons. Capillaries with a non-fenestrated endothelium are occasionally found in the parenchyma. The basal layer is occupied by glial processes abutting on the digitating layer of perivascular connective tissue of meningeal vessels. The endothelium of these vessels is occasionally fenestrated. Trypan blue injected systemically accumulated in the SFO, but not in the deeper areas of the brain. The absence of a blood-brain barrier is suggested in the SFO.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00219805
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  • 89
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    The ultrastructure of the accessory sex organs of the male rat (1978)
    Springer
    Cell & tissue research 192 (1978), S. 39-51 
    Details
    ISSN: 1432-0878
    Keywords: Prostate ; Rat-Anti-Androgens ; Nuclear alterations ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The fine structure of the nuclei of epithelial cells of the dorsal lobe of the rat prostate were studied after administration of three different antiandrogenic compounds. The nucleolus appears to undergo a progressive disorganisation with partial fragmentation and dispersion of its normal components. Different types of intranuclear inclusions were found. The various alterations observed were often encountered within the same section. This may indicate that the nuclear alterations occur in the same compartment of the cell, and represent a dysfunction of integrated biochemical events occurring within this compartment. The findings support a view that the stimulatory secretory effect of androgens is mediated via a ‘secretory center’, located within the nucleolusassociated chromatin. Within this ‘secretory center’, the initial steps of the secretory process, the binding of the DHT receptor complex to DNA is assumed to occur.
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    URL: http://dx.doi.org/10.1007/BF00231021
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  • 90
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    Stereological model system for free cells and base-line data for human peripheral blood-derived small t-lymphocytes (1978)
    Springer
    Cell & tissue research 192 (1978), S. 121-142 
    Details
    ISSN: 1432-0878
    Keywords: T-lymphocytes ; Stereological model system ; Free cells ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Menschliche, in Nylonwolle gereinigte T-Lymphozyten aus dem peripheren Blut dienten als repräsentatives Untersuchungsobjekt zur Schaffung eines neuen stereologischen Modellsystems für freie, sphärische Zellen. Dieses System erlaubt, die Zelle und die darin enthaltenen Strukturkomponenten auf ultrastruktureller Ebene quantitativ zu charakterisieren.
    Notes: Summary T-lymphocytes derived from human peripheral blood and passed through a nylon-wool column, were employed to develop and test a new Stereological model system for free spherical cells, allowing a quantitative characterization of the cell and its components at the ultrastructural level. Electron micrographs were recorded in a hierarchical manner at three different levels of magnification and subjected to point counting procedures. The resulting parameters were expressed in relation to various reference compartments, both absolute and relative. Results indicated that the average volume of a small, non-activated T-lymphocyte was 103.8 μm3, the nuclear volume 47.5 μm3 and the cytoplasmic volume 55.9 μm3. On the average, the cytoplasm contained 30 mitochondria, 0.7 μm3 RER-cisternae, 0.2 μm3 cisternae and vesicles of the Golgi apparatus and about 231,000 free ribosomes (most of them single). The ratio of eu- to heterochromatin volume was 0.5. The design and application of the Stereological model system are discussed with regard to dynamic studies of a variety of free cells, such as macrophages, neutrophilic granulocytes and various lymphocytes.
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    URL: http://dx.doi.org/10.1007/BF00231028
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  • 91
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    Sequential differentiation of intestinal endocrine cells in the fetal mouse (1978)
    Springer
    Cell & tissue research 192 (1978), S. 267-276 
    Details
    ISSN: 1432-0878
    Keywords: Endocrine glands ; Mouse small intestine ; Mouse embryo ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The duodenum and ileum of 15 to 18-day old Swiss ICR mouse embryos were studied with the electron microscope to follow the differentiation of endocrine cells. Endocrine cells were classified on purely morphological characteristics. EC cells appeared at 16 days of gestation in both segments. At the same stage G cells were seen in the duodenum and K cells in the ileum. ECL, and S cells were identified in the duodenum at 17 days. Finally, D cells were seen at 18 days of gestation in the duodenum and ileum. With the electron microscope, endocrine cells were not identified in the small intestine of the mouse before the formation of villi.
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    URL: http://dx.doi.org/10.1007/BF00220744
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  • 92
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    The fine structural localization of acetylcholinesterase in the muscle spindle of the rat (1978)
    Springer
    Cell & tissue research 186 (1978), S. 39-52 
    Details
    ISSN: 1432-0878
    Keywords: Muscle spindle ; Nerve endings ; Acetylcholinesterase ; Cytochemistry ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Muscle spindles from lumbricalis muscles of the rat were incubated for acetylcholinesterase with a modified thiocholine-method of Lewis and Shute and examined by light and electron microscopy. All types of motor nerve ending showed heavy deposits of reaction product in the synaptic cleft. The underlying sarcoplasmic reticulum, transverse tubular system, and, when present, the envelope of sole plate nuclei were also stained. In the sensory region, the reaction was negative in the interface between the plasma membranes of the primary sensory terminal and muscle. One of two secondary sensory endings identified showed distinct reaction product in the cleft; the other secondary sensory ending showed no such reaction. Precipitates were present on the sarcolemma of the intrafusal muscle fibers in the polar and adjacent myotube regions, but not at the spindle equator. Extrafusal and intrafusal myelinated γ-nerve fibers and preterminal motor axons showed staining of the axolemma. Fibers with thick myelin sheaths and preterminal sensory axons were free of acetylcholinesterase activity, as were the unmyelinated nerve fibers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00219653
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  • 93
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    Ultrastructure of the age-involuted adult human thymus (1978)
    Springer
    Cell & tissue research 186 (1978), S. 507-525 
    Details
    ISSN: 1432-0878
    Keywords: Human thymus ; Age involution ; Cellular composition of cortex, medulla and connective tissue ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Age involuted thymus tissue from a middle aged (33 years) and an old (63 years) man have been examined by electron microscopy and compared with thymus tissue from children. Biopsies had been taken during surgical correction of congenital heart defects. The fine structural architecture of cortex, medulla and connective tissue in the remaining lymphatic islands in the adult thymus investigated was not different to the thymus of children. We were surprised to find vigorous lymphocytopoiesis in the cortical regions and to recognize extended areas of medulla with a cellular composition which obviously provides the same microenvironment for T-cell maturation as the medulla of the non involuted thymus. Our findings are discussed in relation to the increasing arguments that the human thymus serves an immunological function throughout life.
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    URL: http://dx.doi.org/10.1007/BF00224939
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  • 94
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    Role of zinc and calcium in the formation and storage of insulin in the pancreatic β-cell (1978)
    Springer
    Cell & tissue research 188 (1978), S. 107-118 
    Details
    ISSN: 1432-0878
    Keywords: Pancreatic β-cells (mouse) ; Formation and storage of insulin ; Role of zinc and calcium ; Culture of islets ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 1. The effects of culture of isolated mouse islets of Langerhans for up to 9 days in media which had been depleted of zinc electrochemically or with the chelating agent Tris-(2-aminoethyl) amine, or of calcium, have been compared. 2. An 83% reduction of extracellular zinc concentration did not adversely affect proinsulin biosynthesis, conversion of proinsulin to insulin, or the ability of cells to store newly formed insulin in granules. When incubation media were depleted of both zinc and calcium the β-cells produced abnormally large electron-lucent granules, consistent with the failure of insulin to crystallise within the granule sac. 3. Very similar results, with formation of large electron lucent granules, were obtained after culture of islets in the absence of calcium but in the presence of normal concentrations of zinc. 4. It is suggested that zinc may play a less critical role in the biosynthesis of proinsulin and its conversion to insulin, while calcium may have a more important function in insulin storage, than has sometimes previously been supposed.
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    URL: http://dx.doi.org/10.1007/BF00220518
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  • 95
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    Cellular organization of the embryonic lobster heart (1978)
    Springer
    Cell & tissue research 188 (1978), S. 171-187 
    Details
    ISSN: 1432-0878
    Keywords: Embryonic heart ; Crustacea (Homarus americanus) ; Cardiac muscle ; Intercellular junctions ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The cellular organization of the embryonic heart of the lobster Homarus americanus was examined in 6-week and 6-month-old animals. The heart wall consists of an outer adventitial layer of fibroblast cells and an inner layer of transversely striated myocardial cells. Present in close association with the myocardium are cardiac neurons, hemocytes and so-called storage cells. Adjacent fibroblasts form fasciae adhaerentes and gap junctions. Adherent junctions also occur between fibroblasts and myocardial cells. Intercalated discs and differentiated membrane regions of close apposition (4 nm) occur between adjacent myocardial cells. The cardiac neurons form a ganglion that contains four small and five large somata. Regions of neuropil are present. Motor axons arising from the cardiac ganglion form neuromuscular synapses with the myocardial cells. The storage cells contain large inclusions and form gap junctions with the myocardial cells. They may supply nutritive material to the developing myocardium. The heart at 6 weeks is about 200 μm long and 160 μm wide. At 6 months, it is about 300 μm long and 250 μm wide. The myocardium at 6 weeks is one cell layer thick, and the cells are from 2–6 μm in maximum width. At 6 months the myocardium is 2–4 cells thick, and the cells are from 6–12 μm in width. Therefore, the myocardium grows by an increase in the number and size of the myocardial cells.
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    URL: http://dx.doi.org/10.1007/BF00222629
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  • 96
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    A freeze-fracture study of tight junctions in the pars convoluta and pars recta of the renal proximal tubule (1978)
    Springer
    Cell & tissue research 186 (1978), S. 121-133 
    Details
    ISSN: 1432-0878
    Keywords: Proximal tubule ; Tight junctions ; Ultrastructure ; Electron microscopy ; Freeze fracturing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The morphology of tight junctions of the renal proximal tubule was studied comparing the pars convoluta and pars recta of rat, golden hamster, rabbit, cat, dog and tupaia. Though some interspecies variations were observed, the convoluted portions of the proximal tubules revealed quite uniformly very leaky tight junctions with mainly 1–2 strands. Along the whole proximal tubule of the rabbit kidney including the pars recta only minor differences of the zonulae occludentes were found. By contrast, the tight junctions of the pars recta in other species were much more elaborate, especially in cat and tupaia, having up to 6 strands and an overall depth of more than 150 nm. The implications of these findings are discussed with special regard to the functional differences between the pars convoluta and pars recta of the proximal tubule.
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    URL: http://dx.doi.org/10.1007/BF00219659
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  • 97
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    An autoradiographic study of satellite cell differentiation into regenerating myotubes following transplantation of muscles in young rats (1978)
    Springer
    Cell & tissue research 186 (1978), S. 535-540 
    Details
    ISSN: 1432-0878
    Keywords: Skeletal muscle ; Satellite cells ; Regeneration ; Electron microscopy ; Autoradiography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Satellite cells were traced autoradiographically during the regeneration of skeletal muscle in young Sprague-Dawley rats. Approximately 31% of the satellite cells in uninjured muscles appeared labelled after three injections of tritiated thymidine; none of the myonuclei were labelled in the same muscles. Four to six days after transplanting the radioactive muscles to non-radioactive littermates, regenerating myotube nuclei in the host appeared labelled. Thus, this study confirms that satellite cells in young rats can differentiate into multinucleated myotubes following muscle injury.
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    URL: http://dx.doi.org/10.1007/BF00224941
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  • 98
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    The junctional connections between the cells of the urinary bladder in the rat (1978)
    Springer
    Cell & tissue research 187 (1978), S. 439-448 
    Details
    ISSN: 1432-0878
    Keywords: Urinary bladder epithelium (Rat) ; Gap junctions ; Tight junctions ; Electron microscopy ; Freeze-fracturing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The junctional connections between the cells of the urinary bladder epithelium in rat have been studied by freeze-fracturing. Tight junctions and desmosomes are known as structural features of the epithelium. In addition, gap junctions (nexus) have been found to connect the epithelial cells in an irregular distribution pattern. The junction size ranges from few assembled particles up to plaques with irregular forms. This may indicate that the gap junctions are mobile structures. The functional significance of the junctions in comparison with electrophysiological data is discussed.
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    URL: http://dx.doi.org/10.1007/BF00229608
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  • 99
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    Ultrastructure of the theca interna of ovarian follicles in sheep (1978)
    Springer
    Cell & tissue research 187 (1978), S. 457-472 
    Details
    ISSN: 1432-0878
    Keywords: Ovarian follicles (sheep) ; Theca interna ; Oestrogen ; Androgen ; Capillaries ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The theca interna of non-atretic ovarian follicles from 2.0 mm in diameter up to the stage shortly following ovulation was studied by light and electron microscopy. In follicles 〈3.0mm in diameter, the theca interna consisted of about 8–12 layers of flattened cells, together with many capillaries and small bundles of collagen. Two main forms of cellular differentiation were seen. These were towards either fibroblast-like cells or presumed steroidogenic cells whose cytoplasm contained large amounts of predominantly smooth tubular endoplasmic reticulum, to which some ribosomes were attached. The majority of cells were of relatively undifferentiated or intermediate structure. In larger follicles up to the early stages of oestrus the theca interna cells became larger and less flattened, and cells rich in tubular endoplasmic reticulum became proportionately more numerous. By 18 h after the onset of oestrus the theca interna was oedematous, and many cells possessed pseudopodia. Many cells also contained numerous lipid droplets, but there were no signs of thecal cell degeneration or death. Shortly after ovulation the basal lamina of the membrana granulosa was incomplete, and it became more difficult to distinguish between theca and granulosa layers. Structural heterogeneity, with two major cell types and cells of intermediate structure, was present at all stages. It was concluded that: (1) the theca interna of 2.0–2.9 mm follicles contained many cells whose structure was compatible with a steroidogenic capacity; (2) changes in the differentiated thecal cells up to the early stages of oestrus were quantitative rather than qualitative, and suggestive of an increased steroidogenic capacity; (3) the accumulation of lipid in many cells of the theca interna by 18 h after the onset of oestrus probably reflected a reduction in steroidogenic activity; and (4) there was no evidence of any structural specialization to facilitate the transport of steroids from the theca interna to the membrana granulosa.
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    URL: http://dx.doi.org/10.1007/BF00229610
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  • 100
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    Ultrastructure of rat pituitary LH gonadotrophs in relation to serum and pituitary LH levels following repeated LH-RH stimulation (1978)
    Springer
    Cell & tissue research 190 (1978), S. 135-149 
    Details
    ISSN: 1432-0878
    Keywords: Serum and pituitary LH ; Rat gonadotrophs ; LH-RH and Granule release, Synthesis and Degradation ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The effects of single and repeated LH-RH injections at 120 min intervals on female rat LH gonadotrophs and on pituitary and serum LH levels were investigated using electronmicroscopy and radioimmunoassay. A temporary stimulation of granule release, of protein and new granule synthesis and of the accumulation of lysosomal structures was found in LH cells after the first LH-RH injection. The temporary stimulations were massively enhanced after the second injection. These consecutive yet in their time-sequence overlapping processes account for the initial depletion of secretory granule content (3–15 min after LH-RH injection), for the subsequent regranulation and accumulation of granules above control levels (60–120 min after injection) and also for the reduction in the number of granules to control levels (150 min after LH-RH injection and thereafter). Increased polymorphic lysosomal structures are believed to be responsible for this reduction of excess granules. The amount of assayable pituitary and serum LH generally corresponds with the morphological changes observed in LH-gonadotrophs, thus further substantiating the above observations. A schema which summarizes the observed morphological and hormonal changes in their time-sequence in response to LH-RH stimulation depicts the short-term regulation of secretory processes in female gonadotrophs.
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    URL: http://dx.doi.org/10.1007/BF00210043
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