摘要:

AbstractRat gestation sites were obtained on days 10 through 16 of normal pregnancy. Light and electron microscopic examination of day‐10 sites revealed a consistent complex pattern of stromal cell morphologies. Six distinct regions were identified: an antimesometrial region of epithelioid decidual cells that form the gestation chamber containing the embryo and extraembryonic membranes; an abembryonic antimesometrial decidual region, the decidual crypt, where the cells are separated by large extracellular spaces; a mesometrial region with granule‐containing cells and mesometrial decidual cells; a region of spiny cells that are lateral to the antimesometrial decidual cells and continuous with the mesometrial decidual cells; and a region of undifferentiated stromal cells adjacent to the myometrium. Between days 12 and 16, the antimesometrial decidua becomes thinner and is eventually sloughed into the newly formed uterine lumen. The role of the antimesometrial decidual cells is discussed with reference to trophoblast invasiveness, protein synthesis, and especially remodeling of the gestation chamber. Differences between decidua and deciduoma are conside

ISSN:0002-9106    

DOI:10.1002/aja.1001720102

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

年代:1985

数据来源: WILEY

摘要:

AbstractThe purpose of this investigation was to examine the suitability of an organotypic lung‐cell culture model for the study of factors influencing fetal lung‐cell differentiation. It has been reported that the use of carbonstripped (hormone‐depleted) bovine fetal calf serum in monolayer cell cultures of fetal rat lung prevents continued epithelial cell differentiationin vitro. In this study, organotypic cultures of fetal rat lung cells taken at day 20 of gestation (late canalicular stage) were prepared with a carbon‐stripped medium. These organotypic cultures were examined by light, scanning, and transmission electron microscopy for comparison with controls prepared with unstripped bovine fetal calf serum. Highly organized three‐dimensional tubular epithelial structures resembling saccules of immature lung were observed within the gelatin sponge matrix. Morphometric analysis of day 20 carbonstripped samples revealed that 74.6% of the epithelial cells in the tubular structures contained osmiophilic lamellar bodies characteristic of type II pneumonocytes. Control specimens had 71.2% cells with lamellar bodies and did not differ significantly from the experimental group. These data are similar to those obtained with organ cultures of fetal rat lung but are in contrast to findings with monolayer culture systems. The observations of this study suggest that (1) the hormones extracted from bovine fetal calf serum by carbonstripping are not solely responsible for the continued fetal lung cell differentiation observedin vitro, and (2) that spatial relationships between lung cellsin vitromay be a significant factor in the control of differ

ISSN:0002-9106    

DOI:10.1002/aja.1001720103

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

年代:1985

数据来源: WILEY

摘要:

AbstractTaste buds in foliate papillae of the rhesus monkey were examined by electron microscopy. Three distinct cell types were identified. Type I cells were narrow elongated cells containing an oval nucleus, bundles of intermediate filaments, several Golgi bodies, and characteristic apical membrane‐bounded dense granules. These cells exhibited morphological variations: some had a moderately dense cytoplasm, perinuclear free ribosomes, and flattened sacs of rough endoplasmic reticulum; others had a more lucent cytoplasm, dilated irregular rough endoplasmic reticulum, lysosome‐like dense bodies, and lipid droplets. Type II cells typically contained a spherical, pale nucleus, a prominent nucleolus, supranuclear and infranuclear Golgi bodies, mitochondria with tubular cristae, and one or two centrioles. This cell type, too, showed some variation in the relative amounts of ribosomes and smooth endoplasmic reticulum, which varied inversely with each other. Type III cells were characterized by a clear apical cytoplasm essentially devoid of ribosomes and containing microtubules. In a few type III cells, the peri‐ and infranuclear regions contained many ribosomes and some rough endoplasmic reticulum. In most Type III cells, there were large numbers of dense and clear vesicles in the peri‐ and infranuclear regions; some of the vesicles were grouped in synapse‐like arrangements with adjacent nerves. The morphological variations exhibited by all three cell types could be accounted for by age differences in each of the cells. This would be consistent with the notion that cell renewal occurs in each of the three cell po

ISSN:0002-9106    

DOI:10.1002/aja.1001720104

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

年代:1985

数据来源: WILEY

摘要:

AbstractOsteoblast and osteoclasts are known to adhere tenaciously to bone surfaces even when the fibrous periosteal covering is removed. Brushsmear isolates and in situ, whole bone mounts of the osteogenic periosteum on the inner and outer calvarial tables of young adult rats were examined at the light microscopic level after exposing the cells by removing the fibrous periosteum. Based on staining, enzymatic activity, and overall morphology, most of the cells could be classified as osteogenic in nature. However, detailed analysis revealed that some cells exhibited certain unique morphologic appearances that suggested the existence of subpopulations or variant forms of the conventional or prototypic osteoblast. Three variant forms were the large nucleate, small nucleate, and multinucleate osteoblast‐like cells, the latter with nuclear numbers ranging from 2–10. The finding of all such forms in smears, short‐term cell cultures, and in situ specimens greatly lessened the probability that the unusual forms were artifactual. Phase contrast microscopic studies and sectioning of cellular isolates for study at both the light and electron microscopic levels provided additional support for the existance of the multinucleate osteoblast‐like cell. The small size of these osteoblast‐like subpopulations and the orientation of the cells to the commonly used plane of section of most histologic bone specimens, particularly with the multinucleate type, could explain why they had escaped earlier

ISSN:0002-9106    

DOI:10.1002/aja.1001720105

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

年代:1985

数据来源: WILEY

摘要:

AbstractWe have studied the ultrastructure of Sertoli‐cell processes that extend into developing germ cells of the ground squirrel (Spermophilus lateralis). In other mammals it is speculated that these processes anchor germ cells to the seminiferous epithelium and transfer materials between Sertoli and germ cells. In the ground squirrel, Sertoli‐cell projections first appear in round spermatids and consist of regions containing numerous mitochondria and intermediate filaments together with areas composed mainly of a fine filamentous matrix. Also present are what may be desmosomelike junctions with adjacent germ cells. During spermatogenesis, numerous changes in the penetrating processes and their internal composition occur. Especially significant are those occurring during the movement of residual cytoplasm basaly over spermatid heads: some Sertoli‐cell processes contain microtubules, mitochondria and vesicular elements, but also present are regions that lack organelles and appear simply as thin lamellae of cytoplasm that line cavernous invaginations of the germ cell. Coated vesicles and pits are present in processes and adjacent germ‐cell regions at all stages of spermatogenesis. Our observations are consistent with the suggestions that Sertoli‐cell processes have an attachment function and that they also may facilitate the movement of residual cytoplasm into the epithelium. Further, they indicate that these structures might be involved with receptor‐mediated

ISSN:0002-9106    

DOI:10.1002/aja.1001720106

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

年代:1985

数据来源: WILEY

摘要:

AbstractThe synthesis and secretion of progesterone by the corpus luteum (CL) may be limited or controlled by transport mechanisms operating between circulating blood and luteal cell cytoplasm. To examine this possibility, the structural features involved in transport, including membrane surface areas and diffusion distances, were quantitated in the CL of 16‐day pregnant rats. One ovary from each of eight rats was fixed by perfusion via a cannula inserted into the parametrial artery, and two CL from each ovary were processed for electron microscopy and examined with standard morphometric techniques. For comparison, one CL from each of a further eight ovaries was diced into small cubes, fixed by immersion, and analyzed similarly. In perfusion‐fixed CL, there was a substantial volume of vascular space (20% of the total) and interstitial space (5%) and an extensive surface area of capillaries (441 mm2per CL). The luteal‐cell membrane had numerous projections which increased its surface area by a factor of 3.08. Almost 60% of the luteal‐cell surface directly faced a capillary, and a further 37% faced interstitial space which probably extended to a capillary surface. Only 3% was in direct contact with a neighboring luteal cell. Despite the extensive interstitial space the harmonic mean thickness, an estimate of likely effective diffusion distance between luteal cell cytoplasm and blood, was only 0.42 μm. This was less than half of the calculated arithmetic mean thickness owing to the presence of surface projections and an uneven capillary endothelium. Results from immersion‐fixed CL were qualitatively similar; but the proportion of interstitial space was only 59% of that in perfusion‐fixed CL, and the contribution of surface projections to the total area of luteal‐cell membranes was significantly reduced. Collectively, these results suggest that membranes and spaces between blood and luteal‐cell cytoplasm are structured so as to minimize tra

ISSN:0002-9106    

DOI:10.1002/aja.1001720107

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

年代:1985

数据来源: WILEY

ISSN:0002-9106    

DOI:10.1002/aja.1001720101

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

年代:1985

数据来源: WILEY