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  • Ultrastructure  (106)
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  • 2020-2024
  • 1975-1979  (106)
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  • 101
    Electronic Resource
    Electronic Resource
    The ultrastructure of the androgenic gland in Porcellio scaber Latr. (terrestrial isopods) (1976)
    Springer
    Cell & tissue research 175 (1976), S. 245-263 
    Details
    ISSN: 1432-0878
    Keywords: Androgenic gland ; Porcellio scaber ; Ultrastructure ; Secretory cycle ; Electron-dense body
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Résumé Les auteurs présentent, dans ce travail, les aspects ultrastructuraux normaux de la glande androgène chez l'oniscoïde Porcellio scaber. On montre, par des phases successives, les modifications morpho-fonctionnelles des organites cellulaires jusqu'à la fin du cycle sécrétoire, qui finit par la dégradation et la destruction des cellules glandulaires, dont la fonction est de type holocrin. Comme produits de cette activité, des corps éléctrono-opaques (grains, agglomerats, lysosomes) et des substances claires apparaissent dans le cytoplasme. Par la destruction de la membrane plasmique, tout le contenu cellulaire est éliminé dans les espaces haemocoeliens, soit par écoulement soit par fragments. Le RE et le chondriome subissent les modifications les plus spectaculaires.
    Notes: Summary This paper presents the normal ultrastructural features of the androgenic gland in Porcellio scaber. It describes the changes in the organelles of its cells through the course of the secretory cycle, which terminates with the regression and destruction of these holocrine glandular cells. As products of this activity, the electron-opaque bodies (granules, lysosomes, agglomerates) and clear substances accumulate in the cytoplasm. With the destruction of the cell membrane, the entire cell content passes into the spaces of the haemocoele. The morphological modifications of the mitochondria and rough endoplasmic reticulum are the most striking changes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00232081
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  • 102
    Electronic Resource
    Electronic Resource
    Demonstration of the existence of a single morphological type of gonadotrophic cell in Ellobius lutescens (Microtinae) by an ultrastructural analysis of their development under various physiological and experimental conditions (1976)
    Springer
    Cell & tissue research 167 (1976), S. 49-64 
    Details
    ISSN: 1432-0878
    Keywords: Ultrastructure ; Gonadotrophic cells ; Rodent ; Ellobius lutescens
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Ultrastructural studies of pituitaries from Ellobius lutescens (immature males and females, adult hypogonadic males, and virgin and pregnant females) show that the gonadotrophic cells are characterized by a lamellar or vacuolar rough endoplasmic reticulum (RER), a spirally-arranged Golgi apparatus, elongated mitochondria and secretory granules of variable density and size (150–500 mμ). Ultrastructural differences between gonadotrophic cells previously determined by light microscopy correspond to changes in the development of the protein synthetic apparatus and in the intensity of hormonal discharge. Type 2 gonadotrophs always appear to be more active than type 1 gonadotrophs. After castration, all gonadotrophic cells develop into the same form of “castration cell”, although type 1 gonadotrophs change more slowly than type 2 cells. Treatment with testosterone induces an inverse development of the gonadotrophic cells which take on the appearance of resting cells similar to those found in immature animals, where the two cell types are also identical. Thus, only one morphological type of gonadotrophic cell can be identified in Ellobius lutescens. Moreover, the gonadotrophic cells of the hypogonadic adult male have the same appearance as those of the female two months after castration, which proves that the negative feedback mechanism which regulates gonadotrophic function is defective in adult male Ellobius lutescens.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00220159
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  • 103
    Electronic Resource
    Electronic Resource
    Ultrastructure of the corneal nerves in the Rat (1976)
    Springer
    Cell & tissue research 172 (1976), S. 133-144 
    Details
    ISSN: 1432-0878
    Keywords: Cornea ; Nerves ; Rat ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructure of the corneal nerves of the rat was studied in tissue fixed by immersion in and by perfusion with glutaraldehyde-containing fixatives. Of the four types of axonal terminal identified in the nerves, those with the features of adrenergic and cholinergic terminals were confined to the nerves at the limbus and were concentrated in the perivascular plexuses. The remaining two types of terminal were found on axons located in all parts of the cornea and on both intraepithelial axons and axons in the stromal nerves. Of these, one contained the numerous mitochondria which occur in the terminals of axons associated with known mechanoreceptors and the second contained variable and often small numbers of both clear and large dense-cored vesicles. While most of the mitochondria-containing terminals were seen in nerves located near the periphery, vesicle-containing terminals were numerous in all of the nerves, and especially in those in the avascular cornea. In material fixed by immersion in glutaraldehyde-paraformaldehyde, the vesicle-containing terminals appeared to be dilated, but in material fixed by perfusion there was little evidence of any increase in the diameter of the axons in the terminal regions. The structure of the terminals was compared with that of the terminals of axons identified in the nerves of the skin and the urinary tract and the differences in the vesicle content of the terminals to those reported in other studies of the corneal nerves was related to the use of different fixation procedures. The possibility that axons possessing such terminals are identical with the beaded axons and both the cholinesterase-positive and fluorescent axons demonstrated in light microscopical studies of the corneal nerves is discussed, and the widespread distribution of the axons in the cornea is equated with the hypothesis that they are afferent in nature and represent the peripheral receptors for pain impulses.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00226054
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  • 104
    Electronic Resource
    Electronic Resource
    Ultrastructure of the organum vasculosum of the lamina terminalis of the japanese quail, Cotumix coturnix japonica (1976)
    Springer
    Cell & tissue research 172 (1976), S. 227-243 
    Details
    ISSN: 1432-0878
    Keywords: Organum vasculosum ; Lamina terminalis ; Ultrastructure ; Quail (Coturnix)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The structure of the organum vasculosum of the lamina terminalis (OVLT) of the Japanese quail has been studied by light and electron microscopy. The OVLT has a palisade arrangement. It forms a part of the terminal plate extending from the optic chiasma to the anterior commissure and is characterized by a special vascular arrangement. The organ consists of ependymal, internal and external zones. The ventricular surface of the organ is covered by non-ciliated ependymal cells characterized by the presence of raspberry-like ventricular protrusions. The ependymal zone is composed of two types of ependymal cells, one being a large, cuboidal cell with voluminous cytoplasmic protrusions suggesting secretion into ventricle, and the other a slender tanycyte with long basal processes which form a structural link between ventricle and vascular plexus of the external surface. The internal zone contains two types of secretory neurons, parvocellular neurons containing a few dense-cored granules 1,000 Å in diameter, and mediocellular neurons containing in their perikarya many larger granules 1,300–1,500 Å in diameter and well developed granular endoplasmic reticulum and Golgi apparatus. The granular formations are usually observed in the Golgi area of both types of cells, thus indicating of their secretory activities. There are three types of nerve terminals in the neuropil: (1) nerve endings containing spherical, dense-cored granules 800 Å in diameter in addition to a majority of synaptic vesicles 400 Å in diameter, which display axosomatic synapses with perikarya of the neurons, (2) nerve endings containing dense-cored granules 1,000 Å in diameter and clear vesicles 400 Å in diameter, and (3) nerve endings containing dense granules 1,300 Å in diameter and clear vesicles. Types 2 and 3 do not display axo-somatic synapses but often show axo-dendritic synaptic contacts with dendrites in the neuropil; thus they are probably axons originating from the parvocellular and mediocellular neurons of this organ. The functional significance of the neurons and axons of the OVLT is discussed and it is suggested that two kinds of neurohormones may be secreted from the OVLT of the Japanese quail.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00226029
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  • 105
    Electronic Resource
    Electronic Resource
    Electron microscopy of the rabbit pineal organ in vitro (1976)
    Springer
    Cell & tissue research 172 (1976), S. 365-377 
    Details
    ISSN: 1432-0878
    Keywords: Pineal organ ; Rabbit ; Organ culture ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The results presented in this study show that the rabbit pineal organ cultured in vitro retained its in vivo fine structure for at least eight days. However, the Golgi complex in the light pinealocytes stopped forming dense core vesicles while vesicle-crowned ribbons increased in number. After addition of norepinephrine to the culture medium, the Golgi complex once more began the production of dense core vesicles. Terminals of light pinealocytic processes then often contained Golgi dense core vesicles in close contact with the cell membrane, suggesting the release of the vesicular content into the intercellular and perivascular spaces. A close topographical relationship between Golgi dense core vesicles and vesicle-crowned ribbons was observed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00399519
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  • 106
    Electronic Resource
    Electronic Resource
    Studies on the fine structure of invertebrate blood vessels (1976)
    Springer
    Cell & tissue research 172 (1976), S. 405-423 
    Details
    ISSN: 1432-0878
    Keywords: Blood vessels ; Invertebrate ; Leeches ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The position, structure and function of the valves within the lateral sinus of the medical leech, Hirudo medicinalis, are described on the basis of vital, light- and electron microscopy. In this species the valvular apparatus consists of multiple elongated fir cone-shaped fibrous villi surrounding the orifices of the latero-lateral and latero-dorsal vessel like a tentacular crest. Each villus is covered by a thin sheet of a continuous endothelium. The valves prevent the backflow of hemolymph during systolic contraction of the lateral sinus. The endothelium contains many small mitochondria and polyribosomes in the perinuclear cytoplasm and it develops deep projections into the underlying connective tissue. Each of these consists of a multilayered system of closely interwoven thin endothelial membranes. The endothelium is anchored to its basement membrane by means of a great number of poorly defined hemidesmosomes. The fibrous tissue of the villi consists mainly of a homogeneous vitreous matrix in which few cellular components and very fine filaments are dispersed. Close to the endothelium this matrix appears to be condensed to form a multilayered framework made out of a basement membrane-like material. Though the valves themselves are devoid of muscle cells, those situated at their base and thus belonging to the vascular wall proper, display some specific morphological features: in particular the nuclei of these cells show a distinct fibrous lamina. Moreover, these muscle cells seem to be innervated only by one type of axon, containing both small, lucent synaptic vesicles as well as some of the dense-core variety. These findings are compared with data from earlier works and are discussed in relation to the hemodynamic functions of this valvular apparatus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00399522
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