摘要:

AbstractHistochemical, x‐ray analytical and scanning and transmission electron microscopical procedures have been utilized to determine the chemical nature, physical appearance and attachments of the tectorial membrane in normal rats and to correlate these results with biochemical data on protein‐carbohydrate complexes. Additionally, pertinent histochemical and ultrastructural findings in chemically sympathectomized rats are considered. The results indicate that the tectorial membrane is a viscous, complex, colloid of glycoprotein(s) possessing some oriented molecules and an ionic composition different from either endolymph or perilymph. It is attached to the reticular laminar surface of the organ of Corti and to the tips of the outer hair cells; it is attached to and enclose the hairs of the inner hair cells. A fluid compartment may exist within the limbs of the “W” formed by the hairs on each outer hair cell surface. Present biochemical concepts of viscous glycoproteins suggest that they are polyelectrolytes interacting physically to form complex networks. They possess characteristics making them important in fluid and ion transport. Furthermore, the macromolecular configuration assumed by such polyelectrolytes is unstable and subject to change from stress or shifts in pH or ions. Thus, the attachments of the tectorial membrane to the hair cells may play an important role in the transduction process at the molecula

ISSN:0002-9106    

DOI:10.1002/aja.1001390402

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

年代:1974

数据来源: WILEY

摘要:

AbstractThis study utilized scanning and transmission electron microscopy of renal tissue to provide new information on the gross and microscopic structure of the kidney. The luminal surface of the proximal convoluted tubule was characterized not only by the border of microvilli, but also by crater‐like depressions, and circumferential folds. In tissue processed for scanning electron microscopy the proximal tubular cells separated along their lateral surfaces clearly exposing the topography of the lateral cell projections of cytoplasm which have been generally unavailable for viewing because of their interdigitation with adjacent cells. The various segments of the nephron were identified on the basis of position in the kidney, general morphology, and the distribution and form of apical microvilli, cilia, or flaps. The external surface of the papillary tip had several parallel furrows into which the collecting ducts opened. Large plaquelike depressions lined the papillary surface. The opposed surface of the renal pelvis had small plaque‐like depressions separated by narrow ridges. Transmission electron microscopy of plastic‐embedded tissue specimens which had been previously dehydrated by the critical point drying method demonstrated that little damage occurred from this proc

ISSN:0002-9106    

DOI:10.1002/aja.1001390403

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

年代:1974

数据来源: WILEY

摘要:

AbstractRetinal photoreceptor degeneration was induced by exposing albino rats to fluorescent illumination at elevated environmental temperatures. Fine carbon particles were injected intravenously or directly into the vitreous body or anterior chamber of the eye. The resulting pattern of invasion, migration, and egression of carbon‐filled phagocytes in eyes with degenerated retinas was reconstructed from a time sequence series of light and electron microscopic tissue sections. Retinal debris, such as damaged photoreceptor outer segments and carbon particles, was most frequently removed by two populations of cells possessing phagocytic properties: mononuclear cells of vascular origin and pigment epithelial cells. After retinal damage, mononuclear cells appeared first in the vitreous body and later, in time sequence, progressively deeper in the inner plexiform layer and out to the bipolar nuclear layer, where they were seen within, or partially within, retinal capillaries. After intravenous carbon injection, however, marked phagocytes were not seen in the retina. Carbon‐filled phagocytic cells were observed in the choroidal connective tissue and blood vessels after intravenous injection, but not after intravitreal injections of carbon. Therefore, retinal phagocytes did not appear to leave the eye through the choroidal circulation. Pigment epithelial cells proliferated by mitotic activity, occurred as single cells separated from Bruch's membrane, and were seen among the degenerated outer segments. After direct exposure to carbon particles, pigment cell phagosomes contained both carbon and lamellated discs of degenerated outer segments. Whether these cells exited from the eye through retinal capillaries or returned to Bruch's membrane to reestablish continuity in the pigment epithelium could not be determi

ISSN:0002-9106    

DOI:10.1002/aja.1001390404

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

年代:1974

数据来源: WILEY

摘要:

AbstractThe participation of Clara cells in the formation of alveolar surfactant and their general metabolism were studied in mice by quantitative autoradiography under electron microscopy after in vivo incorporation of four precursors:3H‐choline,3H‐leucine,3H‐acetate and3H‐galactose.Tritiated choline, a specific precursor of the dipalmitoyl‐phosphatidylcholine‐active fraction of the surfactant, is not incorporated into Clara cells. In contrast,3H‐acetate is first incorporated actively into the endoplasmic reticulum and Golgi apparatus of these cells and, subsequently, in its secretory granules. It is suggested that acetate follows the general metabolism of the cell and/or is transformed into cholesterol. Tritiated leucine is incorporated into the secretory granules, although part of it remains more permanently in the cells. Tritiated galactose is actively incorporated, passes through the Golgi apparatus and eventually appears in the secretory granules.These results suggest that the Clara cell does not synthetize the tensio‐active fraction of the lining layer, as does pneumocyte II, but participates in the synthesis and secretion of proteins, glucides and possibly the cholesterol belonging t

ISSN:0002-9106    

DOI:10.1002/aja.1001390405

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

年代:1974

数据来源: WILEY

摘要:

AbstractOvaries of weanling and juvenile rats were studied by electron microscopic and cytochemical techniques, with particular reference to the role of the Golgi complex in the formation of the zona pellucida. The zona pellucida type of material first appears in the perivitelline space at the stage when the oocyte acquires a single layer of flattened and cuboidal granulosa cells, and is completely formed when the granulosa cells attain a cuboidal shape. The intimate association of the Golgi complex with the oocyte plasmalemma and the presence of mucopolysaccharide in its saccules and vesicles suggests that the Golgi complex of the oocyte plays an important role in the synthesis of the zona pellucida. The zona pellucida of the rat egg consists of a single layer of acid mucopolysaccharide which is structurally distinguishable from the liquor folliculi. Formation of the primary liquor folliculi is attributed to the Golgi complexes in granulosa cells.

ISSN:0002-9106    

DOI:10.1002/aja.1001390406

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

年代:1974

数据来源: WILEY

摘要:

AbstractSites of synaptic transmission between receptor cells and afferent nerves in electroreceptors of elasmobranchs are distinguished by a dense presynaptic ribbon surrounded by synaptic vesicles. Digestion by pronase or protease of thin sections of Epon embedded tissue selectively removes the presynaptic ribbon without affecting other synaptic structures. Presynaptic ribbons are composed in part of protein which differs significantly from other components of the synaptic complex.

ISSN:0002-9106    

DOI:10.1002/aja.1001390407

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

年代:1974

数据来源: WILEY

ISSN:0002-9106    

DOI:10.1002/aja.1001390401

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

年代:1974

数据来源: WILEY