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  • Electronic Resource  (126)
  • 1980-1984
  • 1975-1979  (126)
  • 1965-1969
  • 1860-1869
  • 1978  (126)
  • 1965
  • Electron microscopy  (126)
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  • Electronic Resource  (126)
Years
  • 1980-1984
  • 1975-1979  (126)
  • 1965-1969
  • 1860-1869
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  • 101
    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.
    Type of Medium: Electronic Resource
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  • 102
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 191 (1978), S. 171-182 
    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.
    Type of Medium: Electronic Resource
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  • 103
    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.
    Type of Medium: Electronic Resource
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  • 104
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 194 (1978), S. 79-102 
    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.
    Type of Medium: Electronic Resource
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  • 105
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 194 (1978), S. 183-205 
    ISSN: 1432-0878
    Keywords: Bone marrow ; Heterophil granulocytes ; Granules ; Guineapig ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The development of the heterophil granulocytes in the bone marrow of the guinea pig is described. During the maturation of these cells, three types of granule are formed, not only the azurophil and specific granules already described in other mammals but also a third type of granule referred to here as the nucleated granule. During the process of maturation of the cells, these three types of granule are formed successively. On this basis, two steps can be distinguished in the promyelocyte phase in which primary (nucleated and azurophil) granules are formed, i.e. an early and a late stage, nucleated granules being formed in early and azurophil granules in late promyelocytes. Secondary (specific) granules occur first in myelocytes. In mature heterophils of the guinea pig the granule population is composed of about 85% secondary granules, about 10% azurophil granules, and about 5% nucleated granules. The changes in the granule population during the maturation process were quantified. The observations and calculations point to the occurrence of three mitoses: one in the early and one in the late promyelocyte and the third in the myelocyte.
    Type of Medium: Electronic Resource
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  • 106
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 194 (1978), S. 279-285 
    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.
    Type of Medium: Electronic Resource
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  • 107
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 194 (1978), S. 503-511 
    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.
    Type of Medium: Electronic Resource
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  • 108
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 195 (1978), S. 17-27 
    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.
    Type of Medium: Electronic Resource
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  • 109
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 195 (1978), S. 29-43 
    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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  • 110
    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.
    Type of Medium: Electronic Resource
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  • 111
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 195 (1978), S. 527-533 
    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
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  • 112
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 195 (1978), S. 557-564 
    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.
    Type of Medium: Electronic Resource
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  • 113
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 186 (1978), S. 39-52 
    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.
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  • 114
    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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  • 115
    ISSN: 1432-0878
    Keywords: Endometrium ; Rabbit ; Reproductive cycle ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Changes occurring on the surface of the uterine luminal epithelium of the rabbit during the estrous and progestational stages of the reproductive cycle were examined by scanning and transmission electron microscopy. The findings demonstrate that the uterine epithelium, or endometrium, contains two cell types: ciliated cells and nonciliated, microvillous cells. In estrous animals, ciliated cells, although not very numerous, were usually observed in small groups. However, at increasing intervals of time following mating, ciliated cells progressively disappeared from the endometrium until approximately eight to ten days post coitum, when they became scare. From several hours to four to five days following mating, extensive changes occurred on the surfaces of microvillous cells. When observed by TEM, these elements contained organelles typical of cells involved in the synthesis and secretion of glycoproteins. Furthermore, microvillous cells during this period displayed numerous apical protrusions of different sizes and shapes and containing material of varying electron density. Parallel SEM examinations of the same material confirmed the presence of these protrusions. Some of the protrusions appeared as spheroidal masses attached to the cytoplasm by means of a cytoplasmic strand. Other surface masses were clearly unattached to the cell surface and were distributed (1) on the surface of microvillous cells, (2) on the cilia of adjacent ciliated cells, and (3) on the surface of spermatozoa. Changes occurring on the luminal surface during the early postcoital period are interpreted as an expression of morphodynamic processes likely involving coupled secretion (exocytosis) and resorption (endocytosis) of luminal material. The observations presented here also demonstrate that between six and ten days post coitum, the rabbit endometrium contained increasing numbers of enlarged, nonciliated cells that probably arose by the fusion of smaller, microvillous elements.
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  • 116
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 190 (1978), S. 301-316 
    ISSN: 1432-0878
    Keywords: Trachea (Guinea-Pig) ; Plexus submucosus ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructure of the nerves forming the submucous plexus of cervical and thoracic parts of the trachea was studied in the guinea-pig. Specimens were obtained from 6 animals perfused with warm fixative and from 6 animals in which pieces of trachea were incubated in buffer containing 5-hydroxydopamine before being immersed in cold fixative. Of the two types of axonal terminal identified in the nerves, one contained mainly large dense-cored vesicles, and the second contained numerous small vesicles. In specimens incubated in 5-hydroxydopamine, the small vesicles of the latter terminals exhibited the electron-dense cores which are characteristic of adrenergic axonal terminals. Counts made on perfused specimens showed that, in both the thoracic and cervical parts of the trachea, the density of adrenergic terminals was higher than that of terminals containing mainly large dense-cored vesicles. Overall terminal density was, however, higher in the thoracic than in the cervical part of the trachea, and estimates of nerve size showed that this was associated with the presence in the thoracic plexus of a substantially greater proportion of nerves with less than 6 axons. The possible function of the nerves in the control of the calibre of the submucous blood vessels was discussed.
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  • 117
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 191 (1978), S. 187-203 
    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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  • 118
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 191 (1978), S. 357-362 
    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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  • 119
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 192 (1978), S. 461-474 
    ISSN: 1432-0878
    Keywords: Cerebral vessels ; Venules ; Pericytes ; Electron microscopy ; Microvasculature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Intracerebral venules of the cat were examined to establish criteria for a distinct separation between the venous and arterial system, and to characterize, in greater detail, the mural construction of individual venules. The intracerebral venules were compared with those of other organs. Venules do not have a vascular wall composed clearly of endothelium, media, and adventitia, as is characteristic of arteries and arterioles. The venous endothelium has a similar structure to that of capillaries. The periendothelial cells of the venule differ in shape depending on the vascular diameter. The number of periendothelial cell processes in postcapillary venules increases progressively. Segments in which the basal lamina of the endothelium merges with that of the glia cover a smaller portion of the circumference than in venous capillary loops. In collecting venules, the endothelium is almost completely enveloped by periendothelial cells which have a larger number of filaments. There are no typical smooth muscle cells in the intracerebral venules. The perivascular space becomes wider in collecting venules, contains adventitial cells, phagocytes and a great number of collagen fibers.
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  • 120
    Electronic Resource
    Electronic Resource
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    Cell & tissue research 193 (1978), S. 11-23 
    ISSN: 1432-0878
    Keywords: Tectorial membrane ; Organ of Corti ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The tectorial membrane (t.m.) of mammals, which lies over the organ of Corti, is made up of an agglomerate of protofibrils of varying degrees of hydration. Two types of protofibrils are clearly distinguishable in the mouse t.m. While type-A protofibrils are straight and unbranched (thickness: 110Å) demonstrating a periodic structure (period = 70Å), type-B protofibrils are branched and coiled (thickness: 150–200Å). These protofibrils could be systematically ordered according to the different t.m. zones. Type-A protofibrils predominate in the basal layer and in the entire middle zone, where they are interlaced with strongly hydrated type-B protofibrils. Weakly hydrated type-B protofibrils essentially make up the marginal zone (with the marginal net), the covering net, Hensen's stripe and the immediate contact layer with the limbus.
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  • 121
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    Cell & tissue research 193 (1978), S. 41-59 
    ISSN: 1432-0878
    Keywords: Electrical synapse (frog) ; Electrotonic coupling ; Electron microscopy ; Freeze fracture ; Gap junction ; Mixed synapse ; Motoneuron
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Freeze-fracture replicas and ultrathin sections were used to characterize the gap junctions on the somata and large dendrites of frog motoneurons found earlier by Sonnhof et al. (1977). In freeze-fracture replicas one of the specific features of these relatively frequent gap junctions is the presence of circular regions of non-junctional membrane (“fenestrae”) within areas of typical gap junction appearance displaying P-face particles or E-face pits. Such “fenestrated” gap junctions are mostly associated with membrane specializations indicative of the active zone of a chemical synapse (including vesicle attachment sites in non anaesthetized animals) to constitute mixed synapses. These findings could be verified in ultrathin sections, which revealed that the vesicles of the chemical component of the mixed synapses were spherical and agranular. Our results suggest that the mixed synapses are predominantly axo-somatic and axo-dendritic. The existence of dendro-dendritic gap junctions in the ventral horn region as described by Sotelo and Taxi (1970) was verified in ultrathin sections; they were rare, solely electrotonic in character, and probably represent the morphological basis for the VR-EPSP (Katz and Miledi, 1963; Kubota and Brookhart, 1963), i.e. electrotonic coupling between motoneurons of different spinal segments (Washizu, 1960). Electrotonic coupling can also be demonstrated between motoneurons and afferent fibers of the dorsal root and the lateral column. Electrotonic potentials recorded within motoneurons during electrical stimulation of dorsal root or lateral column precede the chemical postsynaptic potentials; after Mn2+ blockade of chemical synaptic transmission, the electrotonic component persists. Some fibers of these afferent pathways are therefore assumed to act monosynaptically on the motoneuron via mixed axo-somatic and axo-dendritic synapses.
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  • 122
    ISSN: 1432-0878
    Keywords: Olfactory epithelium ; Supporting cells ; Protuberances ; Electron microscopy ; Insectivora ; Talpidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The regio olfactoria of the mole, Talpa europaea, was studied by scanning and transmission electron microscopy. Peculiar structural differentiations, i.e. ovoid-shaped, balloon-like protuberances were found on the surface of the supporting cells. The apical portion of these protuberances contained finely dispersed granular material, whereas in their central part vesicular extensions of the smooth endoplasmic reticulum were observed.
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  • 123
    Electronic Resource
    Electronic Resource
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    Cell & tissue research 193 (1978), S. 543-560 
    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.
    Type of Medium: Electronic Resource
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  • 124
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    Cell & tissue research 195 (1978), S. 227-237 
    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.
    Type of Medium: Electronic Resource
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  • 125
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    Springer
    Cell & tissue research 186 (1978), S. 507-525 
    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.
    Type of Medium: Electronic Resource
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  • 126
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    Electronic Resource
    Springer
    Cell & tissue research 188 (1978), S. 171-187 
    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.
    Type of Medium: Electronic Resource
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