ISSN:0002-9106    

DOI:10.1002/aja.1001880102

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

年代:1990

数据来源: WILEY

摘要:

AbstractThis review centers around studies which have used ethane dimethane sulphonate (EDS) selectively to destroyallof the Leydig cells in the adult rat testis. With additional manipulations such as testosterone replacement and/or experimental induction of severe seminiferous tubule damage in EDS‐injected rats, the following questions have been addressed: (1) What are the roles and relative importance of testosterone and other non‐androgenic Leydig cell products in normal spermatogenesis and testicular function in general? (2) What are the factors controlling Leydig cell proliferation and maturation? (3) Is it the Leydig cells or the seminiferous tubules (or both) which control the testicular vasculature?The findings emphasize that in the normal adult rat testis there is a complex interaction between the Leydig cells, the Sertoli (and/or peritubular) cells, the germ cells, and the vasculature, and thattestosterone, but not other Leydig cell products, plays a central role in many of these interactions. The Leydig cells drive spermatogenesis via the secretion of testosterone which acts on the Sertoli and/or peritubular cells to create an environment which enables normal progression of germ cells through stage VII of the spermatogenic cycle. In addition, testosterone is involved in the control of the vasculature, and hence the formation of testicular interstitial fluid, presumably again via effects on the Sertoli and/or peritubular cells. When Leydig cells regenerate and mature after their destruction by EDS, it can be shown that both the rate and the location of regenerating Leydig cells is determined by an interplay between endocrine (LH and perhaps FSH) and paracrine factors; the latter emanate from the seminiferous tubules and are determined by the germ cell complement. Taken together with other data on the paracrine control of Leydig cell testosterone secretion by the seminiferous tubules, these findings demonstrate that the functions ofallof the cell types in the testis are interwoven in a highly organized manner. This has considerable implications with regard to the concentration of research effort on in vitro studies of the testis, and is discussed together with the need for a multidisciplinary approach if the complex control of spermatogenesis is ever to be properly underst

ISSN:0002-9106    

DOI:10.1002/aja.1001880103

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

年代:1990

数据来源: WILEY

摘要:

AbstractMorphometric studies were performed on 12 mammalian species (degu, dog, guinea pig, hamster, human, monkey, mouse, opossum, rabbit, rat, stallion, and woodchuck) to determine volume density percentage (Vv%), volume (V), and numerical density (Nv) of seminiferous tubule components, especially those related to the Sertoli cell, and to make species comparisons. For most species, measurements were taken both from stages where elongate spermatids were deeply embedded within the Sertoli cell and from stages near sperm release where elongate spermatids were in shallow crypts within the Sertoli cell. Montages, prepared from electron micrographs, were used to determine Vv% of Sertoli cell components in seminiferous tubules. Excluding the tubular lumen, the Sertoli cell occupied from a high of 43.1% (woodchuck) to a low of 14.0% (mouse) of the tubular epithelium. There was a strong negative correlation (r =−0.83;P<0.005) of volume occupancy of Sertoli cells with sperm production. Nuclear volume, as determined by serial reconstruction using serial thick sections, ranged from a high of 848.4 μm3(opossum) to a low of 273.8 μ3(degu). There was no correlation (r=0.02) of nuclear volume with volume occupancy (Vv%) in the tubule. Sertoli cell volume was determined by point‐counting morphometry at the electron‐microscope level as the product of the nuclear size and points determined over the entire cell divided by points over the nucleus. Sertoli cell V ranged from 2,035.3 μm3(degu) to 7,011.6 μm3(opossum) and was highly correlated (r=0.85;P<0.001) with nuclear size. However, there was no significant correlation between the Sertoli cell size (V) and volume occupancy (Vv%; r = 0.13) or sperm production (r = 0.21). Stereological estimates of the numerical density (Nv) of Sertoli cells ranged from a high of 101.9 × 106(monkey) to a low of 24.9 × 106(rabbit) cells per cm3of testicular tissue. There was no correlation of numerical density of Sertoli cells with sperm production (r=0.002). A negative correlation was, however, observed between the numerical density of the Sertoli cells and the Sertoli cell size (r=−0.79;P<0.002). Data from the present study are compared with those previously published. This is the first study to compare Sertoli cell morphological measurements using unbiased sampling techniques. Morphometric data are provided which will serve as a basis for other morphom

ISSN:0002-9106    

DOI:10.1002/aja.1001880104

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

年代:1990

数据来源: WILEY

摘要:

AbstractSodium‐potassium ATPase (Na+K+‐ATPase) is a ubiquitous plasma membrane enzyme which uses the hydrolysis of ATP to regulate cellular Na+and K+levels and fluid volume. This ion pumping action is also thought to be involved in fluid movement across certain epithelia. There are several different genes for this enzyme, some of which are tissue specific. Using an antibody specific for the catalytic subunit of canine kidney Na+K+‐ATPase, we have localized immunoreactivity in the seminiferous and epididymal epithelium of rats of various ages. There was no specific staining of 10‐day‐old rat testis. Faint staining was detected at 13 days and appeared to be associated with the borders of Sertoli cells. At 16 days prominent apical and lateral staining but no basal staining of Sertoli cell membranes was observed. This type of distribution continued until spermatids were present in the epithelium. In the adult rat testis, specific staining was detected in Sertoli cell crypts associated with elongating spermatids, and on the apical and lateral Sertoli cell membrane. In some instances immunoreactivity was concentrated at presumed sites of junctional specializations. In the excurrent ducts of immature and mature rats, Na+K+‐ATPase staining was heavy in the efferent ducts and somewhat lighter in the epididymis. In all regions, the staining was basolateral although there were variations in intensity among the different parts of the epididymis. These results show (1) that rat testis and epididymal Na+K+‐ATPase share some immunological determinants with the canine enzyme; (2) that the epididymal enzyme is located in the conventional basolateral position; and (3) that the distribution of Sertoli cell Na+K+‐ATPase is probably apical and lateral ra

ISSN:0002-9106    

DOI:10.1002/aja.1001880105

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

年代:1990

数据来源: WILEY

摘要:

AbstractWe have investigated, using indirect immunofluorescence techniques, the possibility that vinculin is a component of Sertoli cell ectoplasmic specializations. Affinity‐purified polyclonal antibodies produced against human platelet vinculin were used to probe fixed frozen sections of rat testis. Specific fluorescence occurs in Sertoli cell regions adjacent to spermatids and to basally situated junctional complexes, sites at which ectoplasmic specializations are known to occur. Staining also occurs in Sertoli cell regions associated with tubulobulbar complexes. The antibody also labels focal contacts in cultured human dermal fibroblasts, apical junctional sites of rat epididymal epithelium, and dense plaques of smooth muscle. Our results are consistent with the prediction that vinculin is likely a component of ectoplasmic specializations and are also consistent with the hypothesis that these structures are a form of actin‐associated adhesion comp

ISSN:0002-9106    

DOI:10.1002/aja.1001880106

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

年代:1990

数据来源: WILEY

摘要:

AbstractAfter 20‐day‐old rats are placed on a vitamin‐A‐deficient diet (VAD) for a period of 10 weeks, the seminiferous tubules are found to contain only Sertoli cells and a small number of spermatogonia and spermatocytes. Retinol administration of VAD rats reinitiates spermatogenesis, but a stage‐synchronization of the seminiferous epithelium throughout the testis of these rats is observed. In order to determine which cell type is responsible for this synchronization, the germ cell population has been analyzed in whole mounts of seminiferous tubules dissected from the testes of rats submitted to the following treatments. Twenty‐day‐old rats received a VAD diet for 10 weeks and then were divided into three groups of six rats. In group 1, all animals were sacrificed immediately; in group 2, the rats were injected once with retinol and sacrificed 3 hr later; in group 3, the rats were injected once with retinol, placed on a retinol‐containing diet for 7 days and 3 hr, and then sacrificed. Three rats from each group had one testis injected with3H‐thymidine 3 hr (groups 1 and 2) or 7 days and 3 hr (group 3) before sacrifice. Three normal adult rats (approximately 100 days old) served as controls. Labeled and unlabeled germinal cells were mapped and scored in isolated seminiferous tubules. In group 1, type A1and type A0spermatogonia as well as some preleptotene spermatocytes were present; type A2A3A4In, and B spermatogonia were completely eliminated from the testis. Neither type A1mitotic figures nor3H‐thymidine‐labeled‐type A1nuclei were seen. Three hr after retinol injection (group 2), type A1mitoses, but no labeled type A1nuclei were observed. At 7 days and 3 hr after retinol administration (group 3), type A4and In Spermatogonia as well as type A1spermatogonia were present. A few residual pachytene spermatocytes were found, and some type A0cells were labeled. These results indicate that VAD caused, in addition to an impairment of spermatogenesis at the preleptotene spermatocyte step, a selective momentary arrest of surviving type A1spermatogonia at the G2phase of their cell cycle. Following administration of vitamin A to VAD rats, these type A1cells reinitiated spermatogenesis synchronously and, after several cycless of proliferation and renewai, reconstituted the seminiferous epithelium in a st

ISSN:0002-9106    

DOI:10.1002/aja.1001880107

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

年代:1990

数据来源: WILEY

摘要:

AbstractThe rat perforatorium is the part of the perinuclear theca that underlies the acrosomic system. It appears to be composed of several polypeptides. The main objective of this study was to determine the distribution of seven of these perforatorial polypeptides in the head of the rat spermatozoon. For this purpose, polyclonal antibodies were affinity purified from these polypeptides and tested (1) for their distribution on electron‐microscope sections of late spermatids and spermatozoa by immunogold labeling and (2) for their specificity on Western blots of denatured perforatorial polypeptides by immunoblotting. Imunoblotting showed that all seven of the prominent perforatorial polypeptides had epitopes in common. Immunogold labeling of spermatozoa showed that antibodies against the 13, 13.4, and 16 kDa polypeptides were restricted in their localization to the thicker apical portion of the perforatorium and to the inner zone of the ventral spur. However, antibodies against the 34, 43, 57, and 63 kDa polypeptides reacted with the entire perforatorium but, in addition, reacted with the inner part of the ventral spur and with a portion of the “outer periacrosomal layer” lying between the plasma membrane and the outer acrosomal membrane. These results suggest (1) that there are regional differences in protein composition of the perforatorium, of the outer periacrosomal layer, and of the postacrosomal dense lamina; and (2) that perforatorial polypeptides may not necessarily be restricted to the subacrosomal region, but may also compose portions of the outer periacrosomal layer and postacrosomal dense lamina. Based on both immunoblotting and immunocytochemical results, using an antiactin monoclonal antibody that recognizes all known isoforms of actin, actin was not detected in the perforatorium of step 19 spermatids or spermatozoa. Actin, however, together with the seven perforatorial polypeptides tested, was present in the subacrosomal space of elongating spermatids before the process of condensation of the perforatorium takes

ISSN:0002-9106    

DOI:10.1002/aja.1001880108

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

年代:1990

数据来源: WILEY

摘要:

AbstractA study of manchette development during spermiogenesis inazh/azhmutant mice was carried out by thin‐section transmission electron microscopy with the goal of determining which of the initial steps in spermatid development are aberrant. In the homozygous mutant, spermatogensis was quantitatively normal; but 100% of the sperm nuclei produced had abnormal shapes. The first defect, observed in steps 8–9, was the abnormal positionning of many manchette microtubules. These microtubules were directed to wards regions of the plasma membrane not normally associated with manchette formation, in addition to being located at the caudal rim of the acrosome in the normal region of manchette formation. At steps 10–12, sheets of machette microtubules were often in ectopic positions along the plasma membrane, rather than in association with the nuclear membrane as well. The fine structural appearance of the manchette was generally normal; the defect appeared to be in its positioning within the cell. In many step 8–10 spermatids nuclear invaginations and evaginations were observed, always associated with irregularities in the position of some of the manchette microtubules; these illustrate the capacity of manchette microtubules to deform nuclear shape. The nuclear irregularities remained throughout spermiogenesis. These observations are consistent with the hypothesis that the manchette is involved in at least some aspects of sperm nuclear shaping and that the improper positioning of manchette formation is a likely candidate for the primary abnormality resulting from a defective allele at thea

ISSN:0002-9106    

DOI:10.1002/aja.1001880109

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

年代:1990

数据来源: WILEY

摘要:

AbstractThe modulation of Sertoli cell junctions was studied in the non‐seasonal rooster (Gallus domesticus) and in the seasonally breeding mallard duck (Anas platyrynchos anatidae) using thin sectioning, a junction permeability tracer, and freeze‐fracture replication. During the active spermatogenic phase, the junctions of the duck appeared similar to those of the rooster, therby establishing the duck as an avian model of seasonal modulation of Sertoli cell junctions. As with mammalian seasonal breeders, during the active phase, occluding, gap, and adhering junctions formed a junctional complex all along the long axis of the Sertoli cell. Unlike in mammals, however, no 7‐nm filaments were associated with the occluding junctions. An occluding zonule encircled the Sertoli cell apico‐lateral membrane domain situated above the young germ cells, and constituted a barrier to the entry of lanthanum in the basal third of the seminiferous epithelium. Toward the basal side, forming focal junctions were located on the lateral Sertoli cell membrane domain facing the young germ cells. Toward the apical side, dismantling focal junctions were located on the apical Sertoli cell membrane domain facing the older germ cells.During the duck's testicular regression, 7‐nm filaments were associated with an occluding junction. In freeze‐fracture replicas, each junction was formed by a continuous junctional strand that encircled the apex of the cell. The strands composed a delicate narrow meshwork: an occluding zonule. The blood‐testis barrier was localized near the apex of the epithelium. The seasonal reduction in the number of the strands and the changes in their orientation did not coincide with a change in the permeability of the occluding zonule to lanthanum. In addition, the cyclic disappearance of junction‐associated filaments was not correlated with a change in the permeability of the junctions but with a change in the affinity of junctional particles for one or the other fracture face. It is proposed that the Sertoli cell plasma membrane domains situated apical and basal with respect to the occluding zonule be considered apical and lateral, respectively. The remaining domain facing the basement membrane would therefore be called basal. In the duck, the occluding zonule is not seasonally shifted from the base to the apex of the Sertoli cell. Instead, it remains stationed above the younger germ cells throughout the year. The illusory shift in the location of the blood‐testis barrier during the active phase actually results from the formidable expansion of the Sertoli cell apical membrane domain above the occluding zonule to accommodate the development of germ cells. It follows that the occluding zonules forming the blood‐testis barrier in the nonseasonal breeders actually encircle the apices of the Sertoli cells although they occur in the basal third of the semi

ISSN:0002-9106    

DOI:10.1002/aja.1001880110

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

年代:1990

数据来源: WILEY

ISSN:0002-9106    

DOI:10.1002/aja.1001880101

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

年代:1990

数据来源: WILEY