摘要:

AbstractNine‐month‐old female rats were subjected to right hindlimb immobilization or served as controls for 0, 2, 10, 18, and 26 weeks. They were double‐labeled with bone markers prior to sacrifice. Experimental unloading was produced by immobilizing the right limb against the abdomen with an elastic bandage. Single‐photon absorptiometry was performed on the intact femurs; static and dynamic histomorphometry were performed on 20‐μm thick toluidine blue‐stained, undecalcified cross sections of the tibial shafts. Changes in the continuously immobilized tibiae were compared to those in both tibiae of age‐matched controls.Unloading shut off nearly all periosteal bone formation and accelerates bone marrow expansion over that which occurs in age‐related controls. The effects of unloading appeared to be mediated by recruiting fewer osteoblasts which showed inhibited activity. Furthermore, unloading increased endocortical percentage eroded surface. These histological changes lowered cortical bone mass by inhibiting diaphyseal cross sectional expansion and enlarging the bone marrow cavity. The results support Frost's suggestion that decreased mechanical usage depresses bone modeling‐dependent bone gain by decreasing activation of modeling in the formation mode. It also stimulates bone remodeling‐dependent bone loss by increasing activation of remodeling in

ISSN:0003-276X    

DOI:10.1002/ar.1092290302

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

年代:1991

数据来源: WILEY

摘要:

AbstractThe present study analyzes the regeneration of skeletal muscle in diabetic rats. Intravenous injection of streptozotocin (STZ) was used to induce diabetes. Six weeks later the extensor digitorum longus (EDL) muscles from diabetic rats were either transplanted into diabetic or normal hosts to initiate regeneration. Normal EDL muscle transplants in normal and diabetic hosts were also performed for comparison. One, 2, 4, and 12 weeks after transplantation, the EDL regenerates were morphologically analyzed. Regeneration and formation of neuromuscular junctions were observed in all transplants, including diabetic regenerates in diabetic hosts. The overall mass and myofiber size of the diabetic EDL regenerate in the diabetic host was significantly reduced in spite of complete regeneration. Recovery of the diabetic muscle mass and the myofiber size was observed after transplantation into normal hosts. A reduction in mass and myofiber size was observed in normal EDL muscles transplanted into diabetic hosts. It is concluded that poor recovery of diabetic muscle is related to metabolic and structural alterations in the diabetic host, rather than to innate capacity of the muscle to per se undergo regeneration and reinnervation. The observed enhancement in recovery of diabetic muscle after transplantation in a normal host and deterioration of normal muscle after transplantation in a diabetic host shows that the host environment determines the success of muscle regeneration.

ISSN:0003-276X    

DOI:10.1002/ar.1092290303

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

年代:1991

数据来源: WILEY

摘要:

AbstractThe immunocytochemical localization of an oviductal glycoprotein associated with ovulated eggs was investigated. Using a monoclonal antibody, we studied three regions of epithelium in the golden hamster oviduct. The monoclonal antibody reacted with the oviductal epithelium throughout the fimbriae and isthmus. Intense binding was observed in the ampulla and isthmus, especially in the caudal isthmus. In addition, reactive materials were present in the ovarian bursal sac and lumen of the ampulla. At the ultrastructural level, the monoclonal antibody reacted specifically with putative secretory granules and Golgi apparatus of nonciliated cells in the oviductal epithelium. Other cellular organelles did not react. Quantitative data indicated that the immunolabelings were intense in the ampullar and isthmic cells but weak in the fimbrial cells. Lipid droplet‐like granules of the fimbriae and lysosome‐like vesicles of the isthmus did not react with the monoclonal antibody. In all cases, ciliated cells did not react with the monoclonal antibody. These results suggest that the glycoprotein is primarily produced and secreted by ampullar and isthmic secretory cells and is then accumulated in the ovarian bursal sac. These findings may provide insight into regional and cellular differences in secretion of the golden hamster ovid

ISSN:0003-276X    

DOI:10.1002/ar.1092290304

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

年代:1991

数据来源: WILEY

摘要:

AbstractThe scanning and transmission electron microscopes were used to examine the processes of spermiation and sperm maturation in the marmoset. We observe that the heads of late spermatids are embedded in the apical aspect of the large sleeve‐like columnar portion of Sertoli cells. As spermiogenesis progresses, spermatids become associated with numerous small apical Sertoli cell extensions. These finger‐like processes undergo a sequence of changes during spermiation. Spermatozoa from the caput, corpus, and cauda epididymides were examined. In caput epididymis of marmoset, the apical segment of the spermatozoa extends well beyond the rostral edge of the nucleus and folds back on itself. In sagittal sections, the acrosome exhibits a distinct hook shape. In the corpus, the distinctive hookshaped apical segment of the acrosome is observed in some spermatozoa, but the apical extension is significantly smaller or projects out only slightly beyond the nucleus. In cauda epididymis, the extension is absent. A similar acrosomal hook has been reported in the pigtailed monkey, which is an Old World species. We suggest that changes in acrosome structure during sperm maturation may be fairly widespread among prima

ISSN:0003-276X    

DOI:10.1002/ar.1092290305

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

年代:1991

数据来源: WILEY

摘要:

AbstractCathepsin D (EC3.4.23.5) is an aspartyl endopeptidase involved in lysosomal proteolysis. Its functional role is uncertain. This study was undertaken to determine the cellular and subcellular distribution of cathepsin D in the normal rat ventral prostate and its possible role in the castration‐induced atrophy of the gland. Cathepsin D was localized immunohistochemically to perinuclear lysosomes in secretory cells, in capillary endothelial cells, and, occasionally, in stromal cells of the untreated animal. Castration resulted in an increased number of cathepsin D‐positive cells in the stroma within 24 hr. By 48 hr after castration autophagolysosomes formed in secretory cells and apoptotic bodies appeared in the epithelium. Although apoptotic bodies generally contained immunoreactive cathepsin D, a subpopulation of larger apoptotic bodies, which commonly rested on the basement membrane and contained multiple inclusions, were more variable in cathepsin D expression. The induction of cathepsin D in dendritic cells basally oriented in the epithelium was noted at 4 days of castration. These cells had a phagocytic phenotype, were distributed periodically along the basement membrane, and were not found in ductal epithelia. Treatment with actinomycin D or hydrocortisone to reduce the rate of regression of the ventral prostate blocked the appearance of these cathepsin D‐positive, basally oriented epithelial cells. Our data indicate that this cathepsin D‐positive, phagocytic cell differentiates from a cell resident in the prostatic epithelium. We suggest that it differentiates from basal cells in the secretory tubuloalveolar portion of the gland and that it is involved in the destruction of regressed secretor

ISSN:0003-276X    

DOI:10.1002/ar.1092290306

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

年代:1991

数据来源: WILEY

摘要:

AbstractUsing polyclonal antibodies against a 13 KD human testicular inhibin, immunocytochemical localization studies were carried out in marmoset monkey testes. The pattern as well as the intensity of immunocytochemical staining for inhibin vary substantially during development. In early development (day 1 to 2 months) Leydig cells are the predominant cell types showing intense staining which reaches its nadir at 3 months. Subsequently both Sertoli cells as well as Leydig cells show equal intensity of inhibin staining. Testicular inhibin is likely to play a vital role in cell to cell communication.

ISSN:0003-276X    

DOI:10.1002/ar.1092290307

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

年代:1991

数据来源: WILEY

摘要:

AbstractThe epithelial cell types present in respiratory (= distal alveolarized) and terminal (= distal nonalveolarized) bronchioles in adult human lung were characterized with scanning and transmission electron microscopy (SEM, TEM) and light microscopic cytochemistry, using specific antibodies against surfactant protein SP‐A and mucins, and Alcian blue/periodic acid‐Schiff (AB/PAS) staining.In the respiratory bronchiole, two epithelial cell populations share the same basal lamina: one pseudostratified columnar with ciliated, secretory, and basal cells and the other predominantly simple cuboid with some interspersed flat (type I) cells. The columnar secretory cells show the ultrastructure of mucous cells. Light microscopically, they react with mucin antibodies and contain primarily periodatereactive acid mucins. The mucous cells are the distal secretory cells described by Clara (1937). The cuboid cells are identified as type II (precursor) cells based on ultrastructural criteria for embryonic type II cells (Ten Have‐Opbroek et al., 1988a, 1990a), including a cuboid cell shape, a large and roundish nucleus, rough and smooth endoplasmic reticulum (ER), osmiophilic multivesicular bodies, and dense bodies. These dense bodies in turn frequently exhibit—like those in embryonic type II cells—internal vesicles or lamellae, variability in size and shape, a specific relationship to ER and a widespread cytoplasmic distribution. Finally, the cuboid cells show a cytoplasmic staining pattern for SP‐A. The terminal bronchiole is lined by the columnar cell population.In the respiratory bronchiole, the columnar (bronchial) and cuboid (alveolar) cell populations occupy distinctly different zones (pulmonary artery zone versus remaining wall). The alveolar part of the respiratory bronchiole (called alveolar tubule) defines the proximal border of atruerespi

ISSN:0003-276X    

DOI:10.1002/ar.1092290308

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

年代:1991

数据来源: WILEY

摘要:

AbstractThe spatial distribution of α‐ and β‐myosin heavy chain isoforms (MHCs) was investigated immunohistochemically in the embryonic human heart between the 4th and the 8th week of development. The development of the overall MHC isoform expression pattern can be outlined as follows: (1) In all stages examined, β‐MHC is the predominant isoform in the ventricles and outflow tract (OFT), while α‐MHC is the main isoform in the atria. In addition, α‐MHC is also expressed in the ventricles at stage 14 and in the OFT from stage 14 to stage 19. This expression pattern is very reminiscent of that found in chicken and rat. (2) In the early embryonic stages the entire atrioventricular canal (AVC) wall expresses α‐MHC whereas only the lower part expresses β‐MHC. The separation of atria and ventricles by the fibrous annulus takes place at the ventricular margin of the AVC wall. Hence, the β‐MHC expressing part of the AVC wall, including the right atrioventricular ring bundle, is eventually incorporated in the atria. (3) In the late embryonic stages (approx. 8 weeks of development) areas of α‐MHC reappear in the ventricular myocardium, in particular in the subendocardial region at the top of the interventricular septum. These coexpressing cells are topographically related to the developing ventricular conduction system. (4) In the sinoatrial junction of all hearts examined α‐ and β‐MHC coexpressing cells are observed. In the older stages these cells are characteristically localized

ISSN:0003-276X    

DOI:10.1002/ar.1092290309

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

年代:1991

数据来源: WILEY

摘要:

AbstractThe de‐epithelialization of cells of the upper layer during the phenomena of polyingression and primitive streak ingression was studied by analyzing, from the time of laying to the end of gastrulation, the ultrastructure of the basal lamina underlying the upper layer. The electron density of the basal lamina and associated extracellular materials was enhanced by addition of tannic acid to the fixative. Special attention was also paid to the spatial and temporal distribution of blebs at the basal surface of the upper layer, and to the contribution of the de‐epithelialized cells to the formation of the deep layer. The results indicate that a nascent basal lamina is already present at the time of laying, especially beneath regions of the area pellucida where polyingression is not apparent. From the onset of incubation, the basal lamina rapidly develops, and it is interrupted by a large number of blebs. However, during the first 6–8 h of incubation, i.e., stages 1–2 of Vakaet (Arch. Biol. (Liège) 81:387–426, 1970), a downward movement of deepithelialized cells that insert into the deep layer and form the endophyll persists cranially. This phenomenon of polyingression, which starts during the intrauterine period, probably extends from caudal to cranial and comes to an end by stage 3. During these first three stages, the number of blebs progressively decreases, especially in the cranial part of the area pellucida, and a thicker, continuous basal lamina associated with numerous interstitial bodies is laid down. The caudal part of the upper layer is still actively blebbing at that time. Due to the convergence of this area toward the axis of the blastoderm, which leads to ingression at and elongation of the primitive streak up to and including stage 6, the number of blebs at the basal surface of the upper layer progressively decreases. From stage 7 on, blebs are virtually absent; shortening of the primitive streak and formation of the head process begin. At the level of the head process, primitive streak ingression has ceased and a novel basal lamina is progressively deposited beneath the upper layer. By stage 9, a thick, smooth basal lamina physically separates the upper layer from the head mesenchyme. Summarizing, at the time of gastrulation, the presence of blebs that perforate the basal lamina is correlated with the de‐epithelialization of cells. Before incubation, however, de‐epithelialization of upper‐layer cells occurs before the assembly of the basal lamina. Up to stage 3, the de‐epithelializing cells, randomly distributed in an area in front of the limit of primitive streak ingression, insert into the deep layer and form endophyll. Behind this limit, the de‐epithelialization occurs at the level of the primitive streak only and leads to the formation of mesoblast and, from stage 4 on, of

ISSN:0003-276X    

DOI:10.1002/ar.1092290310

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

年代:1991

数据来源: WILEY

摘要:

AbstractAn electron microscopic analysis has been carried out to compare the neuroglial cells and pericytes within the primary visual cortex, area 17, of young (5–6 years) and old (25–35 years) rhesus monkeys. All of the neuroglial cell types accumulate inclusions within their cytoplasm as they age, and the inclusions within the astrocytes and oligodendrocytes are essentially characteristic of those cell types. The astrocytes probably acquire their inclusions by phagocytosis, and it is suggested that the inclusions in the oligodendrocytes are caused by an agerelated degeneration of the myelin sheaths they produce. The inclusions within the microglia are very heterogeneous. They are more massive than in the other neuroglial cells, so that their inclusions may almost fill the microglia. Pericytes also accumulate inclusions with age and there is evidence to suggest that they empty the contents of their inclusion vacuoles directly into the capillaries. On the basis of counts of the numbers of profiles of neuroglial cells displaying nuclei in thin sections, the only cells to increase in number with age are the microglia. They show an increase of about 44% when the cortices of young and old monkeys are compa

ISSN:0003-276X    

DOI:10.1002/ar.1092290311

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

年代:1991

数据来源: WILEY