摘要:

AbstractThe octopus cell area (OCA) of the posteroventral cochlear nucleus was studied electron microscopically in kittens. The adult OCA, a region of morphologically homogenous neurons receiving heterotypic synapses from the cochlea, was used to define the mature state. The OCA reaches cytological maturity at three weeks postnatally, after progression through four stages, defined on the basis of octopus cell cytology (including relative numbers of somatic and dendritic filopodia and spines) and the frequency, ultrastructure and location of previously defined synaptic terminals. Octopus cell size was also studied in rapid Golgi impregnations. The OCA from birth through three postnatal days (stage 1) showed small neurons, few identifiable synaptic types, small, mostly unmyelinated axons, mitotic cells and undifferentiated glia. Between the fourth and seventh postnatal days (stage 2) distinct type 1 and type 2 endings appeared and dendrites thickened, expanded peripherally and developed mature spines. During stage 3 (8–19 days) loss of filopodia, increased somatic spicules, larger somas and clearer differentiation of type 1 and type 2 synapses occurred. After three postnatal weeks (stage 4) the OCA contained morphologically mature octopus cell somas, all three synaptic types ending upon somas and thick basal dendrites, and fascicles of myelinated fibers. Although cytologically mature, the OCA at this stage (about 20–35 days) is substantially smaller than the adult OCA. This smaller size will facilitate further study of OCA synaptic organizat

ISSN:0002-9106    

DOI:10.1002/aja.1001480102

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractAdult male Syrian hamsters were given daily intraperitoneal injections of epinephrine (1.0 mg/kg) and papaverine, a vasodilator, (60 mg/kg) for a period of ten days. After the treatment period, lanthanum and horseradish peroxidase tracer studies were used to examine the intra‐epithelial component of the blood‐testis barrier. Degenerating tubules often exhibited only Sertoli cells and spermatogonia, or Sertoli cells alone. Sertoli cell processes in the degenerating tubules often arched out from the main cell body to make contact with other Sertoli cell processes, forming a series of vacuole‐like spaces in the germinal epithelium, adluminal to the Sertoli‐Sertoli junctions. At the site of contact between these arching Sertoli cell processes one to eight tight junctions had formed, with hexagonal arrays of Sertoli cell cytoplasmic filaments located immediately adjacent to these junctions. Cisternae of the Sertoli cell endoplasmic reticulum lay deep to the layer of cytoplasmic filaments. It appeared that these junctions had originated after the expulsion of the germinal elements of the seminiferous epithelium. Penetration of the tracers in the degenerating seminiferous tubules was prevented by what appeared to be normal Sertoli‐Sertoli junctions located between apposed Sertoli cells, adluminal to the remaining spermatogonia when these resisted degeneration, or just adluminal to the basal lamina in those tubules in which spermatogonia we

ISSN:0002-9106    

DOI:10.1002/aja.1001480103

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractElectron microscope autoradiography was used to detect the incorporation of3H‐fucose into glycoproteins of toad bladder epithelial cells. After short exposure to3H‐fucose, without a chase period, the Golgi regions of all four cell types were labeled. When exposure to3H‐fucose was followed by chase periods (1, 3, 4 and 6 hours) the apical and basal‐lateral plasma membranes of granular cells were heavily labeled. Apical granules and the cytoplasm of granular cells were also labeled, suggesting that they both provide the means for glycoprotein transfer from the Golgi to the plasma membranes. The heaviest labeling in mitochondria‐rich cells, after the 1‐ and 3‐hour chase periods, was over the apical tubules, although the apical and basal‐lateral plasma membranes were also heavily labeled. After the 4‐ and 6‐hour chases, the labeling of the apical tubules decreased, whereas the labeling of the plasma membranes increased, strongly suggesting that in these cells apical tubules play a major role in the transfer of glycoproteins from Golgi to the plasma membrane. Our results demonstrate that the route of3H‐fucose incorporation into plasma membrane glycoproteins and the rate of glycoprotein synthesis and breakdown are not the same in the two major epithelial cell

ISSN:0002-9106    

DOI:10.1002/aja.1001480104

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractSeminiferous tubules, partially dilated by ligation of the efferent ductules, were examined after treatment with lanthanum. Lanthanum penetrated the intercellular spaces of the seminiferous epithelium, but only to the level of the Sertoli‐Sertoli junctions. Further penetration from the interstitial surface of the tubule was restricted by membrane fusions (tight junctions) at the junctional complex. Lanthanum also penetrated the epithelium from the luminal surface permeating the adluminal intercellular spaces, including the site of the Sertoli‐spermatid junction. The lanthanum occupying the Sertoli‐spermatid junctional site appeared as a slightly narrower electron‐opaque zone than that found in the non‐specialized intercellular areas. The findings clearly reveal that only the Sertoli‐Sertoli junctional site forms a restrictive barrier. In contrast to the specializations of plasma membrane which form the tight junction, the associated filaments and cisterna of endoplasmic reticulum may be components more directly related to maintaining and regulating ce

ISSN:0002-9106    

DOI:10.1002/aja.1001480105

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractThe volume of the extracellular space, which contributes to the microenvironment of neurons, is diminished in the brains of senescent (as compared to adult) rats and an age‐related change in its composition has been hypothesized. To test this hypothesis we have compared the penetration of ruthenium red, a polyanion selectively distributed in the extracellular space, into the dentate gyri of young adult and senescent Fischer 344 rats.Slices of hippocampal formation were fixed by immersion, first in a glutaraldehyde solution containing ruthenium red, then in a solution ofosmium tetroxide containing ruthenium red. A specific area of the dentate gyrus was identified, sectioned and examined by electron microscopy. Dense particles of ruthenium red reaction product were readily localized in intercellular channels and synaptic clefts and the depth of penetration was measured in a standardized manner so as to derive a mean depth of penetration for each of the 11 animals studied. A 28% decrease in the mean depth of penetration of ruthenium red in 25‐month‐old rats, as compared with 3‐month‐old animals, was found.These data indicate an age‐related change in the charge density of the intercellular channels in the dentate gyrus of 25‐month‐old rats. They suggest a primary age‐related change in the charge density of extracellular macromolecules, presumed to be primarily glycosaminoglycans, with a consequent change in water binding capacity and volume of the ex

ISSN:0002-9106    

DOI:10.1002/aja.1001480106

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractThe parathyroid gland of healthy senile dogs aged 8.5 to 15 years was compared with that of mature control dogs by examination with the electron microscope. Preparations fixed by perfusion with glutaraldehyde showed the cytoplasmic matrix of most parenchymal cells to be uniformly dense. None of the cells were of the extremely light type and dark cells were much less frequently noted than in preparations fixed by immersion in glutaraldehyde or osmium tetroxide. Syncytial cells and so‐called colloid follicles were more frequent in senile dogs than in control dogs. It was suggested that the content of the latter structures is not colloid but necrotic substance having origin from the parenchymal cells and that perhaps the occasional cells containing large, membrane‐bound inclusions may be degenerating cells which ultimately produce this necrotic substance. Oxyphil cells and mitochondria‐rich cells of another type were found in all senile dogs, but not in the controls. These cells, especially the mitochondria‐rich cells, frequently contained bizarre mitochondria that were modified in shape, size and arrangement. The most striking feature of these mitochondria was the concentric arrangement of elongated mitochondria which seemed to consist of densely layered cup‐shaped mitochondria. Such mitochondria were noted in all senile dogs aged ten years and over. The significance of mitochondrial pleomorphism in the parathyroid gland of senile dogs was

ISSN:0002-9106    

DOI:10.1002/aja.1001480107

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractDevelopment of chick and rat endocardial cushions (cardiac mesenchyme) was studied histologically (using Nomarski differential interference optics on living and unfixed tissue), ultrastructurally (scanning and transmission electron microscopy), cytochemically (using acidified dialyzed iron as a visual probe for polyanionic material) and autoradiographically (using35S) to elucidate the origin of the mesenchyme, the morphologic sequences leading to cushion formation and secretion of sulfated glycosaminoglycans, if any, by migrating mesenchymal cells. Cushion formation was similar for both species. Mesenchymal cells appeared initially, in 16‐ to 18‐somite embryos, beneath the endothelium (which lacked a basal lamina) of the future atrioventricular canal and outflow tract. The cytoplasm of cushion mesenchymal cells was structurally similar to the endothelium; probably these cells arose by proliferation of the endothelium. Mitotic figures among the “seeded” cells were also numerous. Cushion cells were initially attached to the endothelium by desmosomes but acquired motile apparatus (pseudopodia and filopodia containing microtubules and microfilamentous bundles). Serial sectioning of successively‐aged embryos (20–44 somites) indicated a centrifugal migratory direction. Interaction of the cell processes with extracellular matrix suggested that the latter was used as a migratory substrate. Contact of the advancing wedge of cushion cells with the myocardium produced no alteration in cell structure or mitotic activity. Localization of hyaluronidase‐sensitive, dialyzed iron (DI) precipitates in 250‐nm Golgi vacuoles and hyaluronidase‐sensitive35S‐engendered silver grains over cushion cells indicated that this tissue contributed sulfated macromolecules to the matrix. Localization of hyaluronidase‐labile, DI material in coated, endocytic like vesicles and caveolae also suggested potential modification or conditioning of the matrix by migrating mesenchymal cells. Altogether the study established loci in developing cushions where disruption of the developmental sequence could engender valvu

ISSN:0002-9106    

DOI:10.1002/aja.1001480108

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractFresh pullet eggs (White Leghorn strain) were incubated from 19–26 hours. Blastoderms were fixed in ovo by selected fixatives of various tonicities, postfixed in 2% OsO4, dehydrated in acetone, critical‐point‐dried in liquid CO2, coated with palladium‐gold and observed in a Cambridge S4 scanning electron microscope.Shrunken cells with intracellular yolk granules embossed on the surface are produced by the strongly hypertonic Karnovsky's fixer (Final: 2010 mOsm). Embryos fixed with modified Karnovsky's fixer (Final: 373 mOsm) possess surfaces with irregular microappendages. Swollen cells with few microappendages are obsrved when embryos are fixed in a hypotonic environment (Final: 250 mOsm or less). Ideal fixatives preserve a relatively flat surface, with cells bordered by smooth surface microappendages. For adequate SEM fixation, fixative vehicle should be approximately isotanic for tissue, with aldehyde (2% or less) added to

ISSN:0002-9106    

DOI:10.1002/aja.1001480109

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractRelatively discrete unilateral lesions were made in the lateral portion of the substantia nigra of eight cats and in the medial substantia nigra of two. After a 10‐day survival period the animals were killed, brains were stored in buffered 10% formalin, and frozen sections were stained for degenerating axons and terminals, or by Weil and cresyl violet methods. Electrodes passed through the medial suprasylvian gyrus, pulvinar and/or posterolateral thalamic nucleus and the medial geniculate body. The stria terminalis and hippocampus were undamaged. Degeneration from the lesion followed two paths. One projected through the reticular nucleus into the internal capsule and then ventrolaterally below the putamen to enter the lateral and central amygdaloid nuclei, with degenerated terminals. The second path ran dorsolaterally in the internal capsule to enter the external capsule where some of the fibers spread into the lateral amygdaloid nucleus. It appears that some of the terminals in the lateral amygdaloid nucleus are from the external capsule. Perhaps these connections link the extrapyramidal system to the amygdaloid bod

ISSN:0002-9106    

DOI:10.1002/aja.1001480110

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractNon‐secretory cells lining the ducts of Bowman's gland in the olfactory epithelium of the bandicoot (Isoodon macrourus) are united below the duct lumen by an unusually well‐organized series of desmosomes linked by conspicuous fibrillar bundles with long mitochondria aligned close to the bundles. It is suggested that these junctional specializations may help to maintain an intact duct lumen in a part of the epithelium with considerable intercellular sp

ISSN:0002-9106    

DOI:10.1002/aja.1001480111

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY