摘要:

AbstractIn primates the membrane separating the seminiferous epithelium from the interstitial space is composed of one to three (monkey) or two to six layers (man) of myoid cells associated with one to two layers of fibrocyte‐like adventitial cells. All these cells are separated from each other by irregular spaces filled with various connective tissue intercellular components. Subjacent to the elements of the seminiferous epithelium is a continuous, often redundant, basement membrane. A similar basement membrane‐like material forms a layer next to and over small areas of the plasma membrane of myoid cells. Collagen fibrils grouped in bundles of various sizes are seen in all connective tissue layers but are particularly abundant in the space between the seminiferous epithelium and the innermost layer of myoid cells. Elastic fibrils demonstrated by the Verhoeff iron hematoxylin technique are also present. Composed of a homogeneous material, the elastic fibrils are short, irregular, branching entities with a diameter comparable to or smaller than that of collagen fibrils. In addition, an abundance of microfibrils with a diameter of 12–15 nm is present in the various connective tissue layers. These microfibrils have a densely stained cortex and a lightly stained core. When seen close to the myoid cells, bundles of microfibrils appear to insert on well defined areas next to the plasma membrane. These areas commonly face the patches of electron‐dense material observed on the inner aspect of the plasma membrane of the myoid cells and in which the actin filaments are inserted. Bundles of microfibrils often span the gap between myoid cells of the same layer as well as those of adjacent layers. Microfibrils are also closely related to the surface of elastic fibrils and are seen intertwining with collagen fibrils. Thus microfibrils appear to bridge and bind together adjacent myoid cells and anchor the surface of these cells to the bundles of elastic and collagen fibrils present in the intercellular spaces of the limiting m

ISSN:0002-9106    

DOI:10.1002/aja.1001480402

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

年代:1977

数据来源: WILEY

摘要:

AbstractIn the guinea pig and some other animals, passive immunity is conferred on the developing fetus by passage of immunoglobulin from mother to fetus across the yolk sac. In order to examine the cytological pathway involved in immunoglobulin transport, guinea pig visceral yolk sacs from late in gestation were exposed in vitro to peroxidase‐conjugated guinea pig immunoglobulin G (IgG‐HRP). Tissue was then fixed, incubated to show the site of localization of peroxidase reaction product and prepared for electron microscopy. The results suggested that the first step in the uptake of IgG‐HRP by yolk sac is attachment of the protein to the surface coats of endocytic invaginations at the apical surfaces of the endodermal cells. The endocytic vesicles then appear to pinch off from the surface and move deeper into the cytoplasm. Some of the small endocytic vesicles fuse with large apical vacuoles, which often contain large amounts of reaction product. Other small endocytic vesicles pinch off from the surface, move deeper into the cytoplasm and fuse with the lateral plasmalemma; their protein content is emptied into the intercellular space by exocytosis. From the intercellular spaces the protein presumably diffuses across the basement membrane and connective tissue spaces and enters the vitelline capillary bed. It is postulated that the latter cellular pathway, involving small vesicles and the intercellular spaces, is utilized by those immunoglobulins which are transferred intact across the yolk sac end

ISSN:0002-9106    

DOI:10.1002/aja.1001480403

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

年代:1977

数据来源: WILEY

摘要:

AbstractThis investigation was carried out to determine whether heterologous antisera to alpha fetoprotein (AFP) are embryotoxic to developing rat embryos. Homogeneous rat AFP was isolated and antisera directed against this glycoprotein were produced in rabbits, horse and goat. The effect of the antisera on embryonic development was examined by injecting the antisera intraperitoneally into pregnant rats on the ninth, eleventh and thirteenth days of gestation. The results demonstrated that there was no evidence of increased incidence of fetal abnormalities in 472 surviving fetuses of 42 injected rats. There was no evidence of increase embryonic death or retardation of intrauterine growth following administration of the antisera on the ninth, eleventh and thirteenth days of gestation. The localization of the injected antisera was examined by the indirect immunofluorescent method. The results showed that the heterologous AFP antibodies localized specifically in the visceral yolk sac placenta. No antibody localization was observed in the embryo proper or the chorioallantoic placenta. It is speculated that the localization of AFP antibodies in the visceral yolk sac does not interfere with the embryotrophic function of the visceral yolk sac placenta.

ISSN:0002-9106    

DOI:10.1002/aja.1001480404

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

年代:1977

数据来源: WILEY

摘要:

AbstractThe ultrastructural features of the adrenergic nerve fibers in the pineal glands of the rat, ground squirrel and chinchilla are described. Frequencydistribution histograms of diameters of granulated and non‐granulated vesicles in the adrenergic nerve endings demonstrate that the pineal nerve endings in the chinchilla contain a considerable number of large granulated and non‐granulated vesicles, in contrast to those in the rat and ground squirrel. Synaptic ribbons seen in the pinealocytes of the ground squirrel were often localized near that plasma membrane which lay in close proximity to the axolemma of adrenergic nerve fibers. This observation may indicate that the synaptic ribbons are involved in the functional interconnection between pinealocytes and adrenergic nerve fibers. Localized dilations of the adrenergic nerve fibers were commonly observed in the pineal glands of all species examined. In addition to a variety of axonal constituents, various forms of inclusion bodies were tightly packed within these axonal dilations. The accumulation of the inclusion bodies may represent degenerative changes which occur in the pineal adrenergic nerve fibers in relation to the functional activity of the pineal gl

ISSN:0002-9106    

DOI:10.1002/aja.1001480405

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

年代:1977

数据来源: WILEY

摘要:

AbstractSecretory ameloblasts in lower second molars of 1‐week‐old kittens were studied with the elctron microscope after perfusion‐fixation with and without decalcification.Ameloblast height varied from 40–65 μm. Tomes' process presented a stepped profile with two type‐1 faces (presumably enamel secreting) and one type‐2 face (thought to be non‐secreting). The type‐1 face was associated with extensive membrane infoldings. The enamel facing the type‐1 face was lined by a dense border, and stippled material was present between cell membrane and enamel. The type‐2 face was characterized by minute membrane invaginations and, sometimes, stippled material between enamel and cell membrane. In cross section, the distal part of Tomes' process showed bilateral symmetry, with one dorsal, one ventral and two lateral aspects. It was suggested that enamel formation occurs in three stages. First, interrod enamel on the lateral aspects of Tomes' processes is formed by two adjacent amelblasts. Next, the interrod enamel on the dorso‐ventral aspects of Tomes' processes is formed mainly by the dorsal extension of one Tomes' process. Finally, the enamel rod is formed by one ameloblast.Stippled material was consistently present in the extracellular spaces between Tomes' processes and in irregularly shaped vesicles in the ameloblast apex, and occasionally in large masses between the ameloblast cell bodies. Spherical vesicles within the ameloblast, thought to be lysosomes, also could contain material resembling stippled material. The possibility was considered that stippled material is partly derived from enamel, and finally phagocytosed by ameloblasts. There was no clear morphologic evidence for merocrine secretion playing a role in the formation of either enamel, stippled mate

ISSN:0002-9106    

DOI:10.1002/aja.1001480406

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

年代:1977

数据来源: WILEY

摘要:

AbstractThe present study was undertaken to seek ultrastructural changes in the thyroid gland of the spontaneously hypertensive rat which would contribute to the understanding of previously reported abnormalities in thyroid function. Light and electron microscopic observations and measurements of plasma T3 and systolic blood pressure were recorded from a colony of Wistar‐Kyoto rats (WKY) and of spontaneously hypertensive rats (SHR). The systolic blood pressure of SHR was significantly higher than that of WKY but the plasma T3 levels of the two groups did not differ significantly. After administration of propylthiouracil (PTU), serum T3 levels and systolic pressure of both groups decreased. The size of the thyroid follicles in SHR was highly variable throughout the gland, and the colloid contained unevenly dense areas and cell debris. The follicular cells contained slightly dilated rough surfaced endoplasmic reticulum (ER) and numerous pleomorphic bodies of uneven density. After treatment with PTU, the vessels between the follicles of SHR did not become as dilated as those in WKY but the fine structure of follicular cells in SHR was similar to that of WKY and was characteristic of the typical thyroid response to PTU administration. We suggest that the thyroid in SHR does not respond adequately to the elevated TSH levels reported to be present in these animals, although it can respond to the highly elevated TSH levels which occur with PTU administration. This impairment most probably involves defects in synthesis and/or secretion of thyroid hormones in response to TSH stimulatio

ISSN:0002-9106    

DOI:10.1002/aja.1001480407

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

年代:1977

数据来源: WILEY

摘要:

Abstract14C‐Nicotine·HCl (4.5 mg) was injected into the air space of chick eggs after one day of incubation and the distribution of radioactivity measured on days 3, 5, 7 and 12. By day 3, 98% of the dose had passed from the air space into the egg, proper. The quantity of nicotine in the yolk was highest on day 3 (74% of dose) and decreased steadily until day 12 (52%). The quantity in the albumen increased from 16% on day 3 to a maximum on day 7 and remained constant at 34% until day 12. The embryo contained 0.03% of the nicotine on day 3, and this level increased to 5% by day 12. Nicotine in the allantois increased throughout the study period (0.01% on day 3 to 3% on day 12). Although only 5% of the dose was present in the embryo, the highest concentrations of nicotine observed were in the heart, liver and carcass. The concentrations within these components of the embryo ranged from a minimum of 0.85 μg nicotine/mg dry wt in the heart to a maximum of 2.00 μg nicotine/mg dry wt in the carcass. These levels within the embryo were two to five times higher than the greatest concentrations in the yolk and albumen. The dynamics of nicotine passage from the air space into other components of the fertilized chick egg were clarified. Whereas the conventional expression of teratogenic doses of drugs in chick eggs (i.e., ppm of egg weight) assumes that the compound is distributed uniformaly, this study indicates that such expressions are inaccu

ISSN:0002-9106    

DOI:10.1002/aja.1001480408

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

年代:1977

数据来源: WILEY

摘要:

AbstractRegional differentiation of the plasma membrane and related structures of the exocrine pancreas has been studied ultrastructurally and cytochemically. Fixation with an osmium tetroxide‐silver acetate solution produced abundant fine precipitates on the luminal and basal surface of the centroacinar but not the acinar cells. Staining with dialyzed iron (DI) revealed the heaviest concentration of anionic sites on the luminal plasma membrane of the acinar cells, including the surface of both the intercellular canaliculi and the main lumen. The reactive sites on the apical acinar plasmalemma appeared to consist of discrete globules. DI‐reactivity of the lateral basal membranes was most prominent in the centroacinar cells and essentially absent in the acinar cells but was weak relative to that of the acinar‐cell apical plasmalemma. The lamina lucida of the basement membrane of the duct stained with DI, but that of basement membrane under acinar cells did not. Sialidase digestion prior to DI staining abolished the staining of plasma membranes. These results indicate that duct epithelial cells, including most prominently the centroacinar cells, are chiefly responsible for electrolyte and fluid tran

ISSN:0002-9106    

DOI:10.1002/aja.1001480409

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

年代:1977

数据来源: WILEY

摘要:

AbstractCrown‐rump lengths determined ultrasonically in vivo and in utero in cases of known postovulatory age (33–86 days) agree well with those in length/age tables in current embryological usage. Within the embryonic period proper, however, for a given age, the ultrasonic lengths are usually 1 to 5 mm longer than those of fixed specimens. The probable reasons for this are discus

ISSN:0002-9106    

DOI:10.1002/aja.1001480410

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

年代:1977

数据来源: WILEY

ISSN:0002-9106    

DOI:10.1002/aja.1001480401

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

年代:1977

数据来源: WILEY