inter-Sertoli Cell Junctions Research Articles

Blood-testis barrier: maintained function of inter-Sertoli cell junctions in experimental cryptorchidism in the rat, as judged by a simple lanthanum-immersion technique.

In order to elucidate the mechanisms behind the deleterious effects on the germinal epithelium of experimental cryptorchidism the hypothesis that a leaking blood-testis barrier is the cause of the damage was tested. The permeability of the specialized inter-Sertoli cell junctions to lanthanum after experimental cryptorchidism for 0.5 to 12 days was studied in the rat. In none of the time periods studied lanthanum had penetrated beyond the inter-Sertoli cell junctions. A simple lanthanum immersion technique was used. Testes of 15-days old rats (before the development of the barrier) were used as a positive control of the method, and in these testes lanthanum had penetrated up to the future lumen.

Claudin-11 is over-expressed and dislocated from the blood–testis barrier in Sertoli cells associated with testicular intraepithelial neoplasia in men

In mouse testis, claudin-11 is responsible for the formation of specific parallel TJ strands of the blood-testis barrier (BTB). Concerning the human BTB, there is no information about the transmembrane TJ proteins. We recently demonstrated the loss of functional integrity of the BTB in testicular intraepithelial neoplasia (TIN), associated with a dislocation of the peripheral TJ proteins ZO-1 and ZO-2. Here, we determined the expression and distribution of claudin-11 at the human BTB in seminiferous tubules with normal spermatogenesis (NSP) and TIN. Immunostaining of claudin-11 revealed intense signals at the basal BTB region in seminiferous epithelium with NSP. Within TIN tubules, claudin-11 immunostaining became diffuse and cytoplasmic. Double immunogold labeling demonstrated a co-localization of claudin-11 and ZO-1 at the inter-Sertoli cell junctions. Real-time RT-PCR of laser microdissected tubules showed an up-regulation of claudin-11 mRNA in TIN. Additionally, increased claudin-11 protein was observed by Western blot. We conclude that claudin-11 constitutes a TJ protein at the human BTB. In TIN tubules, claudin-11 is up-regulated and dislocated from the BTB. Therefore, the disruption of the BTB is related to a dysfunction of claudin-11 and not to a failure of its expression.

Coxsackie and adenovirus receptor (CAR) is a product of Sertoli and germ cells in rat testes which is localized at the Sertoli–Sertoli and Sertoli–germ cell interface

The coxsackie and adenovirus receptor (CAR), a putative cell–cell adhesion molecule, has attracted wide interest due to its importance in viral pathogenesis and in mediating adenoviral gene delivery. However, the distribution pattern and physiological function of CAR in the testis is still not clear. Here, we identified CAR in Sertoli cells and germ cells of rats. In vivo studies have shown that CAR resides at the blood–testis barrier as well as at the ectoplasmic specialization. The persistent expression of CAR in rat testes from neonatal period throughout adulthood implicates its role in spermatogenesis. Using primary Sertoli cell cultures, we observed a significant induction of CAR during the formation of Sertoli cell epithelium. Furthermore, CAR was seen to be concentrated at inter-Sertoli cell junctions, co-localizing with tight junction protein marker ZO-1 and adherens junction protein N-cadherin. CAR was also found to be associated with proteins of Src kinase family and its protein level declined after TNFα treatment in Sertoli cell cultures. Immunofluorescent staining of isolated germ cells has revealed the presence of CAR on spermatogonia, spermatocytes, round spermatids and elongate spermatids. Taken together, we propose that CAR functions as an adhesion molecule in maintaining the inter-Sertoli cell junctions at the basal compartment of the seminiferous epithelium. In addition, CAR may confer adhesion between Sertoli and germ cells at the Sertoli–germ cell interface. It is possible that the receptor utilized by viral pathogens to breakthrough the epithelial barrier was also employed by developing germ cells to migrate through the inter-Sertoli cell junctions.

FSH regulates the formation of adherens junctions and ectoplasmic specialisations between rat Sertoli cells in vitro and in vivo

Spermatogenesis is dependent on the ability of Sertoli cells to form mature junctions that maintain a unique environment within the seminiferous epithelium. Adjacent Sertoli cells form a junctional complex that includes classical adherens junctions and testis-specific ectoplasmic specialisations (ES). The regulation of inter-Sertoli cell junctions by the two main endocrine regulators of spermatogenesis, FSH and testosterone, is unclear. This study aimed to investigate the effects of FSH and testosterone on inter-Sertoli cell adherens junctions (as determined by immunolocalisation of cadherin, catenin and actin) and ES junctions (as determined by immunolocalisation of espin, actin and vinculin) in cultured immature Sertoli cells and GnRH-immunised adult rat testes given FSH or testosterone replacement in vivo. When hormones were absent in vitro, adherens junctions formed as discrete puncta between interdigitating, finger-like projections of Sertoli cells, but ES junctions were not present. The adherens junction puncta included actin filaments that were oriented perpendicularly to the Sertoli cell plasma membrane, but were not associated with the intermediate filament protein vimentin. When FSH was added in vitro, ES junctions formed, and adjacent adherens junction puncta fused into extensive adherens junction belts. After hormone suppression in vivo, ES junctions were absent, while FSH replacement restored ES junctions, as confirmed by electron microscopy and confocal analysis of ES-associated proteins. Testosterone alone did not affect adherens junctions or ES in vitro or in vivo. We conclude that FSH can regulate the formation of ES junctions and stimulate the organisation and orientation of extensive adherens junctions in Sertoli cells.

Adult Sertoli Cells Are Not Terminally Differentiated in the Djungarian Hamster: Effect of FSH on Proliferation and Junction Protein Organization1

Sertoli cell number is considered to be stable and unmodifiable by hormones after puberty in mammals, although recent data using the seasonal breeding adult Djungarian hamster (Phodopus sungorus) model challenged this assertion by demonstrating a decrease in Sertoli cell number after gonadotropin depletion and a return to control levels following 7 days of FSH replacement. The present study aimed to determine whether adult Sertoli cells are terminally differentiated using known characteristics of cellular differentiation, including proliferation, junction protein localization, and expression of particular maturational markers, in the Djungarian hamster model. Adult long-day (LD) photoperiod (16L:8D) hamsters were exposed to short-day (SD) photoperiod (8L:16D) for 11 wk to suppress gonadotropins and then received exogenous FSH for up to 10 days. Sertoli cell proliferation was assessed by immunofluorescence by the colocalization of GATA4 and proliferating cell nuclear antigen and quantified by stereology. Markers of Sertoli cell maturation (immature, cytokeratin 18 [KRT18]; mature, GATA1) and junction proteins (actin, espin, claudin 11 [CLDN11], and tight junction protein 1 [TJP1, also known as ZO-1]) also were localized using confocal immunofluorescence. In response to FSH treatment, proliferation was upregulated within 2 days compared with SD controls (90% vs. 0.2%, P < 0.001) and declined gradually thereafter. In LD hamsters, junction proteins colocalized at the basal aspect of Sertoli cells, consistent with inter-Sertoli cell junctions, and were disordered within the Sertoli cell cytoplasm in SD animals. Exogenous FSH treatment promptly restored localization of these junction markers to the LD phenotype. Protein markers of maturity remain consistent with those of adult Sertoli cells. It is concluded that adult Sertoli cells are not terminally differentiated in the Djungarian hamster and that FSH plays an important role in governing the differentiation process. It is proposed that Sertoli cells can enter a transitional state, exhibiting features common to both undifferentiated and differentiated Sertoli cells.

Loss of nectin-2 at Sertoli-spermatid junctions leads to male infertility and correlates with severe spermatozoan head and midpiece malformation, impaired binding to the zona pellucida, and oocyte penetration.

The members of the nectin/CD155 gene family represent a growing class of novel cell adhesion molecules of the immunoglobulin superfamily. In the present study, we describe the generation of a mouse line lacking a functional nectin-2 gene (nectin-2LacZ/LacZ) and analyze the resulting male-specific infertility phenotype. Although nectin-2LacZ/LacZ males produced normal amounts of motile spermatozoa, scanning electron microscopy revealed severe malformations of the spermatozoan head and midpiece. Besides a 4-fold reduction in migration of nectin-2LacZ/LacZ spermatozoa to the oviducts, in vitro binding to zona-intact mouse oocytes was reduced 6-fold. On the other hand, nectin-2LacZ/LacZ spermatozoa bound to zona-free hamster oocytes at near-wild type levels but, remarkably, failed to penetrate. In addition to the previously reported expression of nectin-2 and nectin-3 at Sertoli-spermatid junctions and of nectin-2 at inter-Sertoli cell junctions, we also found nectin-2 to localize at apical cell-cell junctions of the epididymal epithelium. Expression analysis of a LacZ knockin gene into the defunct nectin-2 gene in nectin-2LacZ/LacZ mice provided additional support for our earlier conjecture that in normal testis, nectin-2 is produced exclusively by Sertoli cells. Finally, we found Sertoli-spermatid junctions in nectin-2LacZ/LacZ mice to be virtually devoid of the actin-bundling protein espin, suggesting that ectoplasmic specializations fail to form in the absence of nectin-2. Our functional analyses indicate that the infertility phenotype of nectin-2-deficient male mice is caused by a combination of reduced migration to the oviduct, spermatozoa-zona binding, and sperm-oocyte fusion. We corroborate our previous description of a heterotypic adhesion complex between Sertoli cells and elongated spermatids that is maintained by nectin-2 and nectin-3, respectively.

Estrogen regulates development of the somatic cell phenotype in the eutherian ovary.

Steroids play a critical role in gonadal differentiation in birds, reptiles, and amphibia whereas gonadal differentiation in mammals is thought to be determined by genetic mechanisms. The gonads of female mice incapable of synthesizing estrogens due to disruption of the aromatase gene (ArKO) provide a unique model to test the role of estrogen in regulating the gonadal phenotype. We have shown that in the absence of estrogen, genetically female mice develop testicular tissue within their ovaries. The ovaries develop cells that possess structural and functional characteristics of testicular interstitial cells and of seminiferous tubule-like structures lined with Sertoli cells. Moreover, the ovaries express mRNA for the testis-specific Sertoli cell transcription factor Sox 9 and espin protein, which is specific for inter-Sertoli cell junctions. The development of the testicular tissue in this model can be reverted/postponed by replacing estrogen. When ArKO female mice were fed a diet containing phytoestrogens, the appearance of Leydig and Sertoli cells was postponed and reduced. Furthermore, administration of estradiol-17beta decreased the number of Sertoli and Leydig cells in the ovaries. These findings constitute definitive evidence that estrogen plays a critical role in maintaining female somatic interstitial and granulosa cells in the eutherian ovary.

Dynamic testicular adhesion junctions are immunologically unique. I. Localization of p120 catenin in rat testis.

In the seminiferous epithelium, morphologically diverse junctions mediate inter-Sertoli and Sertoli-germ cell adhesive contact, but the molecular composition of such junctions is not well known. At prototypical adherens junctions, proteins termed catenins bind to the intracellular domain of classic cadherins and regulate the strength of adhesion. Using a panel of monoclonal antibodies (5A7, 8D11, and 15D2), p120 catenin (p120) was localized in postnatal and adult rat testis cryosections and touch preparations by immunofluorescence. Immunoprecipitation of testis homogenates showed that at least four p120 isoforms were expressed from Postnatal Day 7 through adulthood. Both inter-Sertoli and Sertoli-germ cell junctions were p120-positive, however, individual p120 monoclonals were localized to specific junctions. The 5A7 and 8D11 antibodies colocalized with beta-catenin and plectin at inter-Sertoli and Sertoli-spermatocyte junctions. At inter-Sertoli junctions, p120 was juxtaposed to but did not colocalize with f-actin. Thus, p120 is likely a component of inter-Sertoli desmosome-like junctions. In contrast, the 15D2 monoclonal antibody specifically immunostained Sertoli-round spermatid and inter-Sertoli cell junctions in a dynamic pattern. From the time that round spermatids form to their differentiation into elongate spermatids, Sertoli-round spermatid 15D2 immunostaining cycled from a single mass to a curvilinear pattern, and finally to punctate structures scattered throughout the epithelium. This localization and stage-specific immunostaining pattern indicated that 15D2 recognized Sertoli-round spermatid desmosome-like junctions. Between Sertoli cells, 15D2 immunostained newly formed junctions (at Postnatal Days 21 through 43), but not mature junctions in the adult. From these data, we conclude that p120 is a component of most, if not all, desmosome-like junctions, and that desmosome-like junctions between different cell types contain a unique molecular composition.

Study on the formation of specialized inter-Sertoli cell junctions in vitro.

An in vitro culture system using Sertoli cells was employed to assess the expression of component genes pertinent to occluding junctions (OJ) (such as zonula occludens-1, ZO-1), anchoring junctions (AJ) (such as N-cadherin and beta-catenin), and communicating gap junctions (GJ) (such as connexin 33, Cx33) when they are being formed in vitro. Freshly isolated Sertoli cells from 20-day-old rats with a purity of greater than 90% were cultured either at low- (2.5 x 10(4) cells/cm(2)) or high-cell density (0.6 x 10(6) cells/cm(2)) on Matrigel-coated dishes for 7 days in vitro to allow the establishment of specialized junctions. In low cell density Sertoli cell cultures, specialized OJ such as tight junctions did not form during the entire culture period when assessed by the transepithelial electrical resistance (TER). In high cell density cultures, there was an increase in ZO-1 expression in days 1 to 3 preceding the establishment of tight junctions by day 4. When Sertoli cells were cultured at both cell densities, there was a transient increase in Sertoli cell N-cadherin expression, which peaked by days 4-5, suggesting the time course for the establishment of AJ may overlap with the OJ. A significant increase in the expression of Sertoli cell beta-catenin was also detected by days 5-7 in the high but not low cell density cultures. The expression of Cx33 was also enhanced at days 4-5 in both high and low density cultures. These results suggest that OJ, AJ, and GJ are formed between Sertoli cells in high density cultures, whereas OJ cannot be formed in low density cultures. A full-length cDNA clone coding for rat testicular beta-catenin was also isolated. The deduced amino acid sequence of rat beta-catenin yielded a 781 amino acid polypeptide which displayed a 99.9% identity with the mouse homolog. Conditioned medium of germ cells induced a dose-dependent stimulation on Sertoli cell beta-catenin expression, suggesting germ cells may affect the N-cadherin/beta-catenin-mediated signal transduction pathway. In summary, this study illustrates several target genes can be used as molecular markers to monitor the inter-Sertoli junction formation. This system should be applicable to screen new male contraceptives in vitro targeted at the interference of junction formation by disrupting the timely expression of genes necessary for junction establishment and/or maintenance.

Pubertal Development of Intersertoli Cell Junctions in the Testis of Corriedale Ram Lambs

The ultrastructure of the tight junctional complex of pubertal ram lamb Sertoli cells was studied in immersion-fixed samples and related to clinical data and a light microscopical classification of the degree of spermatogenesis attained in the corresponding seminiferous tubule. Although the process followed the general mammalian developmental trend for tight junction complex formation, 2 unusual ultrastructural features were detected: the presence of an active Golgi complex during the early stage of tight junction formation and the transitory presence of ribosomes on both faces of the ectoplasmic cisternae bordering the developing junctions. The significance of these findings is discussed.

Development of the blood-testis barrier and changes in vascular permeability at puberty in rats.

The effectiveness of the blood-testis barrier to water-soluble substances was assessed in rats of various ages by measuring the volumes of distribution of Cr-EDTA and albumin, and estimating the proportion of the testis made up by interstitial tissue and tubular lumen by morphometric techniques on cryostat sections of frozen tissue. The interstitial tissue volume fell from 15 days to reach adult values at about 30 days of age. A lumen was present in some animals at 15 days, and it enlarged progressively to reach adult levels at about 45 days of age. The 1-h Cr-EDTA space began to fall after 25 days, and reached adult values by 33 days; in rats aged 25 and 30 days, the Cr-EDTA space was almost twice the measured interstitial tissue volume, but even in the older rats, the Cr-EDTA space remained appreciably greater than the interstitial tissue volume. The 20-h albumin space did not begin to fall until after 33 days, and had still not reached adult values in rats aged 44 days. Thus, the functional barrier to water-soluble markers develops later and more gradually than the barrier to electron-opaque markers as used by previous authors, and its appearance correlates more closely with enlargement of the tubular lumen than with formation of the inter-Sertoli cell junctions. The rate at which the albumin space approached its final value was used to calculate the vascular permeability to albumin. This rose to a maximum between 25 days and 33 days of age, and then fell again, although adult values had still not been reached by 44 days of age.

Postnatal development of bovine Sertoli cells.

The fine structure of bovine Sertoli cells was studied from the 4th to the 40th week post natum in order to correlate the progressive acquisition of normal adult morphology with functional development. The considerable increase in tubular size during the first 20 weeks is due to the proliferation of both presumptive Sertoli and germ cells. Aside from this, the presumptive Sertoli cells are seen to expand radially and lengthen considerably. From then on however, the observed increase in tubular diameter during the later period of postnatal development is solely due to the great increase in the number of germ cells. Presumptive Sertoli cells undergo morphological differentiation to mature Sertoli cells during the first 28 weeks of proliferative development. The maturation process includes distinct changes in cell shape, nucleus and cellular organelles, as well as an increase in and differentiation of Sertoli cell surface specializations. At 24 weeks the development of inter-Sertoli cell junctions has reached a point of differentiation where, in our opinion, a functional blood-testis barrier can be expected. During the first 8 weeks an extensive development of rough endoplasmic reticulum and a well-developed Golgi apparatus can be observed, which suggests a high secretory activity in the presumptive Sertoli cells at this time. We speculate that these secretory activities may play a role in the formation of the basal lamina which is extremely well developed during early postnatal life. The subsequent reduction of the basal lamina correlates well with diminished secretory activity in the Sertoli cells.

The blood-testis barrier in sterile blue fox - silver fox hybrids compared with that in normal foxes of both species.

The integrity of the blood-testis barrier in the blue fox, the silver fox and hybrids of these 2 species was compared at the ultrastructural level during the breeding season by use of a lanthanum penetration technique. In the normal blue and silver fox, penetration of the tracer was blocked at the level of the inter-Sertoli cell junctions, whereas these junctions were permeable in the hybrids, permitting penetration of lanthanum into the adluminal compartment of the seminiferous epithelium. Spermatogenesis in the hybrids was found to be arrested at the early pachytene stage of meiotic prophase. The observed permeability of the inter-Sertoli cell contacts in the hybrids indicates a lack of occluding junctions, and this may be partly the cause of the sterility in these animals.

Evaluation of the ultrastructural changes in the human Sertoli cell in testicular disorders and the relationship of the changes to the levels of serum FSH

Sertoli cell ultrastructure was compared in men with testicular disorders (hypospermatogenesis; germ cell aplasia) and men with normal testes to determine if any specific cytological change could be correlated with diminished feedback from the testis resulting in elevated serum FSH levels. The normal Sertoli cell contained smooth endoplasmic reticulum, mitochondria and variable numbers of lipid inclusions, lipofuscin, crystals of Charcot-Böttcher and specialised inter-Sertoli cell junctional complexes. The principal abnormalities in Sertoli cells of men with testicular disorders were: 1) dilated vesicles of smooth endoplasmic reticulum and occasional expansions of the intercellular space; 2) increased numbers of cytoplasmic filaments; and 3) with germ cell aplasia inter-Sertoli cell junctions were complexly arranged due to interdigitation of Sertoli cell processes. Occasionally, increased lipid and lipofuscin aggregations were seen and in germ cell aplasia, aggregations of cytoplasmic glycogen were often present. Although these changes were seen more consistently with germ cell aplasia they were observed frequently with hypospermatogenesis where some tubules contained Sertoli cells with normal features. No correlation was found between abnormal Sertoli cell cytology and serum FSH levels.

Differentiation of the rat seminiferous tubules between 13 and 19 days of age.

The differentiation of rat seminiferous tubules have been studied in 13 to 19 days old. Testicular weight and tubular cross-sectional area were more than doubled during this period. The percentage of tubules with more than 10 primary spermatocytes increased from 4% to 90%, and the lanthanum excluding ability of the inter-Sertoli cell junctions (the blood-testis barrier) showed a similar increase but two days later. ABP production in vitro increased more than twentyfold from day 13 to day 19 of age. It is concluded that the differentiation of Sertoli cell function and the appearance of primary spermatocytes are temporally correlated which supports the assumption that the function of the Sertoli cells is important for initiation and maintenance of spermatogenesis.

Specialized cell contacts and the blood-testis barrier in the seminiferous tubules of the domestic fowl (Gallus domesticus).

The ultrastructure of Sertoli-Sertoli and Sertoli-germ cell surface specializations in the domestic fowl was studied in material fixed by vascular perfusion through the thoracic aorta. Three main types of surface specializations were found between adjacent Sertoli cells. These are focal tight junctions, desmosome-like devices, and a specialization characterized by the presence of long and dilated subsurface cisternae of rough endoplasmic reticulum. Typical inter-Sertoli cell junctions similar to those of mammals were absent. Germ cells were attached to Sertoli cells mainly by desmosome-like devices of varying appearance. The junctions between Sertoli cells and elongating or elongated spermatids, "the mantle", consisted of only slight condensations of filamentous material in the Sertoli cell. The tight junctions between adjacent Sertoli cells were efficient in preventing lanthanum from passing towards the lumen beyond the level of the spermatogonia.

Fine structure of the modified sertoli cells in the terminal segment of the seminiferous tubules of the bull, ram and goat

The ultrastructure of the epithelial cells in the terminal segment of the seminiferous tubules was studied in the bull, ram and goat. These cells were characterized by membrane-bounded spaces and intercellular dilatations, and abundant microtubules and microfilaments. The presence of vacuolated nucleoli and typical inter-Sertoli cell junctions in the cells of the terminal segment confirms the concept that these cells are actually modified Sertoli cells. Ligation of the efferent ductules in the bull for 24 h had no harmful effect upon the blood-testis barrier in the terminal segment.

Effects of experimental cryptorchidism on the ultrastructure and function of the Sertoli cell and peritubular tissue of the rat testis.

Within 7 days of the surgical induction of cryptorchidism, the Sertoli cells demonstrated an accumulation of lipid inclusions and dilatations of smooth endoplasmic reticulum. Aggregations of large vacuoles were observed at the basal aspects of the Sertoli cells and appeared to arise from local dilatations of the intercellular spaces between opposing inter-Sertoli cell junctions. These modifications of the inter-Sertoli cell junctional complexes disappeared as the cryptorchid state persisted, though some observations suggest that the associated membranes form complexly arranged bodies. The function of the Sertoli cells was altered in the cryptorchid testis as demonstrated by severe reduction in androgen binding protein (ABP) production by the 4 week cryptorchid testis and the lack of measureable ASP within the caput epididymidis. Serum FSH and LI-I levels became significantly elevated within 14 days of establishing cryptorchidism, suggesting diminished feedback from the damaged testis. Continuation of cryptorchidism was associated with progressive widening and folding of the peritubular tissue of the seminiferous tubule leading to bizarre arrangements of the tunics propria. The results are consistent with the proposal that in association with degeneration of the germ cells of the cryptorchid testis, the structure and function of the Sertoli cells are acutely sensitive to the raised intra-abdominal temperature.

Hormonal regulation of Sertoli cell differentiation.

This study was carried out to determine the possible hormone dependence of the postnatal changes on the cytological characteristics of the rat Sertoli cell. Neutralizing antisera to rat follicle stimulating hormone (AS/FSH) and sheep luteinizing hormone (AS/LH) were prepared in rabbits and made monospecific by suitable absorption. Groups of male Sprague-Dawley rats were injected from birth to 32 days with either AS/FSH, AS/LH, AS/LH + testosterone propionate (TP), or normal rabbit serum (NRS). In control 33-day-old animals, Sertoli cells displayed most of the fine structural characteristics of the adult type. Their nuclei were highly infolded and showed an elaborate shape. Euchromatin was largely predominant with a few heterochromatic masses associated with the nuclear envelope or with the prominent nucleolus. The perinuclear area of cytoplasm was particularly rich in mitochondria, smooth endoplasmic reticulum (SER) and Golgi complexes. Inter-Sertoli cell junctions were fully developed. After AS/LH treatment, the nuclei were reduced in size and adopted a smooth surface with very few infoldings. In addition, many clumps of heterochromatin were apparent close to the nuclear envelope and the number of the nucleoli was reduced. Sertoli cell cytoplasm was severely atrophied following AS/HL administration, showing sparse mitochondria, SER and Golgi profiles. Addition of TP to the AS/LH treatment failed to reverse these cytoplasmic changes but resulted in a reappearance of the membrane infoldings of the nuclear envelope and normal numbers of nucleoli. On the other hand, AS/FSH treatment did not induce any apparent morphological change in the Sertoli cell nuclei. The cell volume was reduced but most of the cytoplasmic organelles were apparently present in normal numbers. However, extensively dilated cisternae of the endoplasmic reticulum containing floccular material were a common and impressive change. No modifications were detected in the Sertoli cell junctions in any of the experimental groups. ABP testicular and epididymal levels were diminished in both AS/FSH and AS/LH treated groups, but the reduction was more marked in the latter. ABP levels remained low when TP was administered with the AS/LH. These observations indicate that in the absence of LH morphological differentiation and growth of Sertoli cells are severely inhibited and that FSH withdrawal causes specific changes in the ER that may indicate a trophic action on it. The failure of TP to reverse the effects of AS/LH administration could be attributed to the possibly severe FSH inhibition induced by the high testosterone plasma levels.

Blood-testis barrier: evidence for intact inter-Sertoli cell junctions after hypophysectomy in the adult rat.

To study the hormonal dependence of the blood-testis barrier, adult rats were hypophysectomized and the ultrastructural integrity of the inter-Sertoli cell junctional complex was examined at various times with a lanthanum tracer technique. It was found that the structural integrity of the inter-Sertoli cell junctions and their capacity to exclude lanthanum from the adluminal compartment were preserved up to 35 days after hypophysectomy. Furthermore, transport of newly formed spermatocytes through the inter-Sertoli cell junctions still occurred 20 days after hypophysectomy. It is therefore concluded that the function of the inter-Sertoli cell junctional complex is not directly dependent on gonadotrophic or androgenic hormones, but is regulated by other mechanisms.