Localization of plasminogen activator and inhibitor, LH and androgen receptors and inhibin subunits in monkey epididymis

Epididymis is a site of sperm maturation and storage. Limited and directed-proteolysis regulated by plasminogen activator (PA), plasminogen activator inhibitor type-1 (PAI-1) and other related factors may play an essential role in these processes. Our previous studies have demonstrated that rat epididymis expressed luteinizing hormone receptor (LHR), tissue type (t) and urokinase type (u)PA, mRNAs, and tPA activity was stimulated in vitro by human chorionic gonoadotrophin (HCG). In the present study we further examined localization of mRNAs for tPA, uPA, LHR, androgen receptor (AR), as well as inhibin subunits alpha, betaA and betaB in rhesus monkey epididymis. Using in-situ hybridization with digoxygenin-labelled cRNA probes, we have demonstrated that tPA and PAI-1 mRNAs were localized in epithelial cells of adult monkey epididymis. uPA mRNA was localized in the same areas, but to a much smaller extent. tPA, uPA and PAI-1 mRNAs were greatly expressed in the caput and corpus of adult epididymis than in other regions. In-vitro experiments showed that both tPA and uPA activities in epididymal cells were dramatically stimulated by HCG, but not by follicle stimulating hormone (FSH). LHR (but not FSH receptor) and AR mRNAs were localized in the epithelial cells of the epididymis. However, LHR mRNA was detected in both adult and immature infant monkeys, whereas AR was found only in the adult. Inhibin alpha, betaA and betaB mRNAs were also detected in this organ, betaA mRNA being more strongly expressed in the caput than in other regions of the epididymis. We suggest that LH and androgen may be the key hormones in coordination with the PA-PAI-1 system in regulating epididymal differentiation and sperm maturation.      

Hormonal regulation of tissue-type plasminogen activator and plasminogen activator inhibitor type-1 in cultured monkey Sertoli cells

Sertoli cells play a central role in the control and maintenanceof spermatogenesis. Isolated Sertoli cells of mouse and rattestes have been shown to secrete plasminogen activator (PA)and a plasminogen activator inhibitor type-1 (PAI-1) in culture.In this study, we have investigated the hormonal regulationof PA and PAI-1 activities in cultured monkey Sertoli cells.Sertoli cells (5x10⁵ cells/well) isolated from infant rhesusmonkey testes were preincubated at 35°C for 16 h in 24-wellplates precoated with poly(D-lysine) (5 µg/cm²) in 0.5ml McCoy's 5a medium containing 5% of fetal calf serum and furtherincubated for 48 h in 0.5 ml serum-free medium with or withoutvarious hormones or other compounds. PA as well as PAI-1 activitiesin the conditioned media were assayed by fibrin overlay andreverse fibrin autography techniques respectively. The Sertolicells in vitro secreted only tissue-type PA (tPA), no detectableamount of urokinase-type PA (uPA) could be observed. MonkeySertoli cells were also capable of secreting PAI-1. Immunocytochemicalstudies indicated that both tPA and PAI-1 positive staininglocalized in the Sertoli cells, spermatids and residual bodiesof the seminiferous epithelium; Northern blot analysis furtherconfirmed the presence of both tPA and PAI-1 mRNA in monkeySertoli cells. Addition of follicle-stimulating hormone (FSH)or cyclic adenosine monophosphate (cAMP) derivatives or cAMP-generatingagents and gonadotrophin-releasing hormone (GnRH) agonist orphorbol ester (PMA) to the cell culture significantly increasedtPA activity. PAI-1 activity in the culture was also enhancedby these reagents except 8-bromo-dibutyryl-cAMP, forskolin and3-isobutyl-1-methylxanthin (MIX) which greatly stimulated tPAactivity, whereas decreased PAI-1 activity, implying that neutralizationof PAI-1 activity by the high level of tPA in the conditionedmedia may occur. These data suggest that increased intracellularsignals which activate protein kinase A (PKA), or protein kinaseC (PKC) can modulate Sertoli cell tPA and PAI-1 activities.The concomitant induction of PA and PAI-1 by the same reagentsin the Sertoli cells may reflect a finely tuned regulatory mechanismin which PAI-1 could limit the excession of the proteolysis. plasminogen activator inhibitor type-1/Rhesus monkey/Sertoli cells/tissue-type plasminogen activator     

Endocrinology and Paracrinology: Hormonal regulation of tissue-type plasminogen activator and plasminogen activator inhibitor type-1 in cultured monkey Sertoli cells

Sertoli cells play a central role in the control and maintenanceof spermatogenesis. Isolated Sertoli cells of mouse and rattestes have been shown to secrete plasminogen activator (PA)and a plasminogen activator inhibitor type-1 (PAI-1) in culture.In this study, we have investigated the hormonal regulationof PA and PAI-1 activities in cultured monkey Sertoli cells.Sertoli cells (5x105 cells/well) isolated from infant rhesusmonkey testes were preincubated at 35°C for 16 h in 24-wellplates precoated with poly(D-lysine) (5 µg/cm²) in 0.5ml McCoy's 5a medium containing 5% of fetal calf serum and furtherincubated for 48 h in 0.5 ml serum-free medium with or withoutvarious hormones or other compounds. PA as well as PAI-1 activitiesin the conditioned media were assayed by fibrin overlay andreverse fibrin autography techniques respectively. The Sertolicells in vitro secreted only tissue-type PA (tPA), no detectableamount of urokinase-type PA (uPA) could be observed. MonkeySertoli cells were also capable of secreting PAI-1. Immunocytochemicalstudies indicated that both tPA and PAI-1 positive staininglocalized in the Sertoli cells, spermatids and residual bodiesof the seminiferous epithelium; Northern blot analysis furtherconfirmed the presence of both tPA and PAI-1 mRNA in monkeySertoli cells. Addition of follicle-stimulating hormone (FSH)or cyclic adenosine monophosphate (cAMP) derivatives or cAMP-generatingagents and gonadotrophin-releasing hormone (GnRH) agonist orphorbol ester (PMA) to the cell culture significantly increasedtPA activity. PAI-1 activity in the culture was also enhancedby these reagents except 8-bromo-dibutyryl-cAMP, forskolin and3-isobutyl-1-methylxanthin (MIX) which greatly stimulated tPAactivity, whereas decreased PAI-1 activity, implying that neutralizationof PAI-1 activity by the high level of tPA in the conditionedmedia may occur. These data suggest that increased intracellularsignals which activate protein kinase A (PKA), or protein kinaseC (PKC) can modulate Sertoli cell tPA and PAI-1 activities.The concomitant induction of PA and PAI-1 by the same reagentsin the Sertoli cells may reflect a finely tuned regulatory mechanismin which PAI-1 could limit the excession of the proteolysis.     

Expression of tissue type and urokinase type plasminogen activators as well as plasminogen activator inhibitor type-1 and type-2 in human and rhesus monkey placenta

The distribution of mRNAs and antigens of tissue type (t) and urokinase type (u) plasminogen activators (PA) plus their corresponding inhibitors, type-1 (PAI-1) and type-2 (PAI-2) were studied in human and rhesus monkey placentae by in situ hybridisation and immunocytochemistry. Specific monkey cRNA and antibodies against human tPA, uPA, PAI-1 and PAI-2 were used as probes. The following results were obtained. (1) All the molecules tPA, uPA, PAI-1 and PAI-2 and their mRNAs were identified in the majority of the extravillous cytotrophoblast cells of the decidual layer between Rohr's and Nitabuch's striae and in cytotrophoblast cells of the chorionic plate, basal plate, intercotyledonary septae and cytotrophoblast cells of the chorionic villous tree. (2) Expression of uPA and PAI-2 was noted in villous trophoblast whereas tPA and PAI-1 were mainly concentrated where detachment from maternal tissue occurs. (3) No expression of tPA, uPA, PAI-1 and PAI-2 was observed in the basal plate endometrial stromal cells, chorionic plate connective tissue cells, septal endometrial stromal cells or villous core mesenchyme. (4) The distribution of probes observed following in situ hybridisation is generally consistent with the immunofluorescence pattern of the corresponding antigens and no significant interspecies differences were noted. It is possible that both decidual and extravillous trophoblast cells of placentae of human and rhesus monkey are capable of producing tPA, uPA, PAI-1 and PAI-2 to differing extents. Coordinated expression of these genes in the tissue may play an essential role in the maintenance of normal placentation and parturition. The differences in distribution we observed are consistent with the suggestion that coordinated expression of tPA and its inhibitor PAI-1 may play a key role in fibrinolytic activity in the early stages of placentation and separation of placenta from maternal tissue at term. On the other hand, uPA with its inhibitor PAI-2 appears mainly to play a role in degradation of trophoblast cell-associated extracellular matrix, and thus may be of greatest importance during early stages of placentation.     

Cloning of cDNAs and the differential expression of A-type cyclins and Dmc1 during spermatogenesis in the Japanese eel, a teleost fish.

We cloned A-type cyclins (cyclins A1 and A2) and Dmc1 cDNAs from the eel testis. Cyclin A1 mRNA was predominantly expressed in the livers, ovaries, and testes of the eels. In contrast to cyclin A1 mRNA, a very high expression of cyclin A2 mRNA was observed in the brains, livers, kidneys, spleens, ovaries, and testes of the eels. Dmc1 mRNA was predominantly expressed in the testes and ovaries; expression in the brain was also detected. In the eel testis, a few type-A spermatogonia incorporating 5-bromo-2'-deoxyuridine (BrdU) were seen before the initiation of spermatogenesis by hormonal induction. On day 1 after hormonal induction, the number of BrdU-labeled spermatogonia increased remarkably, and after 3 and 6 days, many labeled type-B spermatogonia were also observed. The expression of cyclin A2 increased 1 day after the induction of spermatogenesis and reached a plateau after 6 days, when many type-B spermatogonia with high proliferative activity were found. In contrast, the expression of cyclin A1 mRNA was detected after 9 days, coincident with the first appearance of spermatocytes. Cyclin A1 mRNA was localized in germ cells of all stages, from primary spermatocytes to round spermatids, whereas cyclin A2 mRNA was specifically localized in spermatogonia, secondary spermatocytes, round spermatids, and testicular somatic cells, including Sertoli cells. Dmc1 was localized only in the earlier stages of primary spermatocytes; before this stage, cyclin A1 mRNA was not detectable. Overall, cyclin A2, Dmc1, and cyclin A1 are expressed in spermatogenic cells sequentially before and during meiosis in the eel testis.     

IL-1beta stimulates urokinase-type plasminogen activator expression and secretion in human dental pulp cells

Plasminogen activator (PA) is the enzyme that converts plasminogen to its active form, plasmin, which is involved in various physiological and pathological phenomena. The conversion is catalyzed by two types of PA, urokinase-type PA (uPA) and tissue-type PA (tPA). We investigated the effect of the inflammatory cytokine interleukin-1beta (IL-1beta) on PA secretion in human dental pulp cells. When the cells were stimulated by IL-1beta, PA activity in the medium was clearly increased in a time- and dose-dependent manner. This PA activity in the medium was reduced after immunoprecipitation with anti-uPA antibody, and uPA protein was detected in the immunoprecipitated fraction by Western blotting. However, no such effect was observed with anti-tPA antibody. In the IL-1beta-stimulated cells, expression of uPA mRNA was enhanced whereas expression of tPA mRNA was less. The IL-1beta-stimulated uPA mRNA expression and PA activities in the cell lysate and medium were reduced by the tyrosine kinase inhibitors herbimycin A and genistein, and by the NFkappaB inhibitor pyrolidinedithiocarbamate, and were augmented by the tyrosine phosphatase inhibitor sodium orthovanadate. These observations suggest that IL-1beta stimulates uPA production via activation of NFkappaB and tyrosine phosphorylation, and also secretion of the enzyme, and that the uPA/plasmin system appears to be involved in inflammation in human dental pulp.     

Differential effects of nonsteroidal antiinflammatory drugs on the IL-1 altered expression of plasminogen activators and plasminogen activator inhibitor-1 by articular chondrocytes

OBJECTIVE: To determine the in vitro effects of several nonsteroidal antiinflammatory drugs on the IL-1 altered expression and activity of tPA, uPA and PAI-1 by articular chondrocytes. METHODS: Bovine chondrocytes were cultured in alginate gel beads. Cells were treated with IL-1alpha in the presence or absence of drugs at various concentrations. Expression of mRNA for the plasminogen activators (uPA and tPA) and their inhibitor (PAI-1) were analyzed by RT-PCR-ELISA. The protein content of PAI-1 in culture media was deter mined by ELISA. PA activity was measured by a functional assay. RESULTS: All tested NSAIDs dose dependently inhibited the IL-1 induced mRNA expression of tPA, whereas only indomethacin and tiaprofenic acid were also able to reduce the expression of uPA. Expression of PAI-1 was elevated by IL-1 without an accompanying increase in secreted amounts of the inhibitor. Indomethacin, naproxen and tiaprofenic acid stimulated the release of PAI-1 into culture media, whereas meloxicam also induced expression of PAI-1 above IL-1 stimulated levels. CONCLUSION: In conclusion, our studies indicate that NSAIDs preferentially inhibit tPA expression by bovine articular chondrocytes. By increasing the production of PAI-1 at therapeutical concentrations meloxicam could reduce PA activity, whereas the other NSAIDs tested mainly enhanced the release of this inhibitor from the extracellular matrix. In how far this would affect the enzyme-inhibitor balance within cartilage has to be determined in further studies.     

Preliminary studies on the role of plasminogen activator in seminal plasma of human and rhesus monkey

Two types of plasminogen activators (PA), tissue type (tPA)and urokinase type (uPA), were identified in the seminal plasmaof both the human and the rhesus monkey. We studied the possiblerelationship between PA activities in the seminal plasma andthe sperm counts and motility and demonstrated that: (i) PAactivity in human seminal plasma from infertile patients wasassociated with immotile spermatozoa; (ii) the treatment offertile men with testosterone enanthate (TE) to induce azoospermiawas accompanied by an increase in seminal PA activity; (iii)when monomer T4 (isolated from multiglycosides of Tripterygiumwilforddi) was administered to fertile male rhesus monkeys toinduce azoospermia, PA activities in seminal plasma increasedconsiderably; and (iv) immunocytochemistry studies showed thatboth uPA and PAI-1 antigens were localized on the surface ofhuman spermatozoa, indicating that human spermatozoa were capableof binding uPA and PAI-1 through their receptors or forminga complex. These data demonstrate that seminal PA activity maybe related to azoospermia, and possibly, to the fertilizingcapability of spermatozoa in primates. human/plasminogen activator/rhesus monkey/seminal plasma ³Present Address: Department of Medical Biochemistry and Biophysics,Umeå University,S-901 87, Umeå, Sweden ⁴Present Address: Department of Pathology, McMaster University,OntarioL8N 3Z5, Canada     

Localisation cellulaire de la sécrétion de l’inhibine B testiculaire

Inhibin B is a testicular peptide hormone that regulates FSH secretion in a negative feedback loop. Inhibin B is a dimer of an α and βB subunit. In adult testis, the cellular site of production of these subunits is still controversial: Leydig cells, Sertoli cells and/or germ cells. The immunohistological localization (monoclonal antibodies anti α and anti βB) of both sub-units and the expression patterns of their mRNA (in situ hybridization with RNA probes) were examined in adult testicular biopsies with normal spermatogenesis or spermatogenetic arrest. In all testes, Sertoli cells and Leydig cells showed positive immunostaining for inhibin α subunit and expressed inhibin α subunit mRNA. Conversely, germ cells expressed the βB peptide (located from pachytene spermatocytes to round spermatids) and the βB subunit mRNA (located from spermatogonia to round spermatids). These results agree with the recent opinion that inhibin B is possibly a joint product of Sertoli cells and germ cells in adult men and it may be used as a serum marker of spermatogenesis.     

Prolactin delays gonadotrophin-induced ovulation and down-regulates expression of plasminogen-activator system in ovary

This study was conducted to determine whether prolactin (PRL) suppresses gonadotrophin-induced ovulation and disturbs the co- ordinated gene expression of tissue type plasminogen activator (tPA) and plasminogen activator inhibitor type-1 (PAI-1) in rat ovary. Immature female rats were injected with 10 IU pregnant mare's serum gonadotrophin to stimulate follicle growth, and 48 h received different doses of prolactin followed by 7 IU human chorionic gonadotrophin (HCG). The oviducts were examined for the presence of ova, and the amounts of tPA and PAI-1 mRNA present in the ovary were measured at various times after the hormone treatment. PRL had no significant effect on ovarian weight but caused a dose-dependent decrease in ovulation number. In the control animals receiving HCG alone, 13.3 +/- 1.3 (mean +/- SEM) ova/oviduct were found; while in animals receiving HCG plus 50, 100 or 200 microg PRL, the ovulation number was dose- dependently suppressed by 53.6, 66.9 and 76% respectively at 18 h after treatment. PRL suppression of HCG-induced ovulation was time-dependent. By 24 h after treatment, the number of ova in the oviducts in HCG- and HCG plus PRL-treated groups was not significantly different. PRL also suppressed HCG-induced tPA gene expression in a dose- and time- dependent manner. At all time points examined, tPA mRNA content of whole ovaries and granulosa cells (GC) in PRL-treated groups was lower than in the HCG-treated controls. The activities of PAI-1 in ovarian extracellular fluid (OEF) and PAI-1 mRNA in the theca-interstitial cells (TI) in the PRL-treated groups were higher than in the HCG- treated controls. The highest stimulation by PRL of PAI-1 activity in OEF and of PAI-1 mRNA in TI was observed at 9 h and 6 h after HCG treatment respectively. The localization of tPA and PAI-1 antigens in the ovaries was consistent with changes in the mRNA and activity levels. These data suggest that PRL temporarily delays, but does not completely inhibit, HCG-induced ovulation, which may be caused by a suppression of PA-mediated proteolysis.      

In situ stromal expression of the urokinase/plasmin system correlates with epithelial dysplasia in colorectal adenomas.

An increase of urokinase-type plasminogen activator (uPA) and a decrease of tissue-type PA (tPA) have been associated with the transition from normal to adenomatous colorectal mucosa. Serial sections from 25 adenomas were used to identify PA-related caseinolytic activities by in situ zymography, blocking selectively uPA or tPA. The distribution of uPA, tPA, and type 1 PA inhibitor mRNAs was investigated by nonradioactive in situ hybridization, and the receptor for uPA was detected by immunostaining. Low- and high-grade epithelial cell dysplasia was mapped histologically. Results show that 23 of 25 adenomas expressed uPA-related lytic activity located predominantly in the periphery whereas tPA-related activity was mainly in central areas of adenomas. In 15 of 25 adenomas, uPA mRNA was expressed in stromal cells clustered in foci that coincided with areas of uPA lytic activity. The probability of finding uPA mRNA-reactive cells was significantly higher in areas with high-grade epithelial dysplasia. uPA receptor was mainly stromal and expressed at the periphery. Type 1 PA inhibitor mRNA cellular expression was diffuse in the stroma, in endothelial cells, and in a subpopulation of alpha-smooth muscle cell actin-reactive cells. These results show that a stromal up-regulation of the uPA/plasmin system is associated with foci of severe dysplasia in a subset of colorectal adenomas.     

Localization of cytochrome P450 aromatase and estrogen receptors alpha and beta in testicular cells--an immunohistochemical study of the bank vole

Age- and light-dark cycle-induced changes in immunoexpression of aromatase and estrogen receptors alpha and beta were studied in testes of a seasonally breeding rodent, the bank vole. Seasonal breeding can be mimicked by exposure to different light cycle regimes. In testes of animals that were exposed to long light cycles of 18 h light and 6 h darkness aromatase was in Leydig cells and seminiferous tubules, mainly in spermatocytes, whereas in animals exposed to short light cycles (6 h light and 18 h darkness), only Leydig cells exhibited positive immunostaining for aromatase. Whatever the age of animals, immunostaining for estrogen receptor alpha was restricted to Leydig cells, whereas estrogen receptor beta immunoreactivity was mainly confined to Sertoli cells of both of immature and adult animals, independently of the regimes of light. Additionally, in testes of animals that were exposed to long light cycles, estrogen receptor beta immunoreactivity was observed in seminiferous tubules. Nuclei of germ cells, predominantly spermatocytes and elongated spermatids, were strongly positive which correlated well with aromatase immunoreactivity. As far as we know, the present study is the first study that describes immunoexpression of aromatase and both estrogen receptors alpha and beta in testis of the bank vole. We provide strong evidence that estrogens are not only produced in Leydig cells but also in germ cells in this rodent. These female hormones may play a physiological role in testis, likely in the development of germ cells during spermatogenesis.     

Fas expression correlates with human germ cell degeneration in meiotic and post-meiotic arrest of spermatogenesis

Degeneration of human male germ cells was analysed by means of light (LM) and transmission electron (TEM) microscopy. The frequency of degenerating cells was correlated with that of Fas-expressing germ cells in human testes with normal spermatogenesis (n = 10), complete early maturation arrest (EMA) (n = 10) or incomplete late maturation arrest (LMA; n = 10) of spermatogenesis. LM analysis of testis sections with normal spermatogenesis indicated that degenerating germ cells were localized in the adluminal compartment of the seminiferous epithelium. TEM showed that apoptotic cells were mostly primary spermatocytes and, to a lesser extent, round or early elongating spermatids. Apoptotic germ cells appeared to be eliminated either in the seminiferous lumen or by Sertoli cell phagocytosis. An increased number of degenerating cells was observed in testes with LMA as compared with normal testes and testes with EMA of spermatogenesis (P < 0.001, Wilcoxon's rank sum test). Comparison of these results with those obtained from immunohistochemistry experiments demonstrated a tight correlation between the number of apoptotic cells and the number of Fas-expressing germ cells (P = 0.001, Spearman's rank = 0.69). These findings suggest that altered meiotic and post-meiotic germ cell maturation might be associated with an up-regulation of Fas gene expression capable of triggering apoptotic elimination of defective germ cells.     

A new approach to quantification of Sertoli cells that avoids problems associated with the irregular nuclear surface

A new approach to quantification of Sertoli cells is described. The number of Sertoli cells per testis was calculated from the number of spermatids per testis, the number of spermatids per Sertoli cell apex, and the correction for the lifespan of spermatids enumerated per testis. To evaluate this method under different physiological conditions, testes from 28 adult (4-20-year) stallions obtained in the nonbreeding season (December-January) and from 28 adult stallions in the breeding season (June-July) were compared. Number of Sertoli cells per gram parenchyma was similar between seasons. However, the number of Sertoli cells per testis was significantly greater in the breeding season. In verification of this method, the number of spermatids per Sertoli cell apex was similar to that calculated as the ratio of spermatids to Sertoli cell in the same stallions. Likewise, absolute values similar to those of other approaches further verify the validity of this approach.     

Mechanical stress enhances expression and production of plasminogen activator in aging human periodontal ligament cells

Plasminogen activator (PA) converts plasminogen to plasmin, and plasmin activates the kinin cascade and latent extracellular matrix metalloproteases. The periodontal ligament serves to anchor the tooth to the alveolus and functions as a cushion between these hard tissues to migrate occlusal force during mastication. We reported previously that repeated mechanical tension force (MTF) as an experimental model of a traumatic occlusion, increased PA activity in human periodontal ligament derived fibroblast (hPLF) cells. In this study, the influence of in vitro cellular aging on MTF-stimulated PA activity in hPLF cells was studied. Aged hPLF cells produced a significantly higher PA activity when compared with those of young hPLF cells in response to MTF in a time- and magnitude-dependent manner. tPA mRNA levels in aged cells were higher than those in young cells, whereas PAI-1 mRNA remained unchanged and uPA mRNA was not detected. Because MTF-stimulated PA activity from hPLF cells was increased by in vitro cellular aging, aging of the periodontal ligament may affect the severity of the inflammation and the degradation of the extracellular matrix of periodontal ligament tissue by producing a large amount of PA in response to excessive force such as a traumatic occlusion.     

Expression of growth differentiation factor 9 (GDF9) and its receptor in adult cat testis

Oocyte-secreted growth differentiation factor (GDF) 9 plays an essential role during follicle maturation through actions on granulosa cells. Despite its critical role in female reproduction, GDF9 expression, signalling and function are less well characterized during spermatogenesis. The purpose of this study was to investigate temporal and spatial expression and potential cellular targets of GDF9 in the adult cat testis. Our result confirmed that GDF9 is stage-specifically localized in the cytoplasm of round spermatids and pachytene spermatocytes of the cat seminiferous epithelium. In particular, activin receptor-like kinase (ALK) 5, the type I receptor of GDF9, is principally localized in the cytoplasm of round spermatids. Smad2/3, signal transducers for GDF9 signalling pathway, is mainly immunolocalized in the cytoplasm of germ cells, Sertoli cells and Leydig cells, but the expression in germ cells are weaker than in Sertoli cells. The expression pattern of ALK5 and Smad2/3 show that GDF9-ALK5-Smad2/3 may not be the only signalling pathway for testicular cell to respond to GDF9. Overall, our results demonstrate that GDF9 is a germ cell-specific factor in the adult cat testis, and that GDF9 regulates the tight junctions of Sertoli cells by paracrine secretion, and regulates the germ cells by autocrine secretion.     

Alfa-inhibin and transferrin in human fetal testis

Aim of this research was to investigate the immunohistochemical localization of alfa-inhibin and transferrin in the human fetal testis. In addition, an attempt was made to identify the Sertoli cells in primary cell cultures of fetal testes by the demonstration of the mRNA for transferrin and the presence of the FSH receptor. 15 fetal testes (8-12 weeks) were utilized. The results of this study show: 1. In sections, immunoreactivity for alfa-inhibin was present in the interstitial cells, whereas transferrin was localized in Sertoli cells; 2. After 20 days of primary culture: a) the percentage of immunoreactive cells for both the substances was about 15%; b) the presence of FSH receptor and the expression of transferrin mRNA were observed in 12-15% of cells. These findings suggest: 1. alfa-inhibin and transferrin are present in the human fetal testis; 2. the expression of transferrin mRNA and the presence of the FSH receptor permit the identification of the Sertoli cells in primary cultures of fetal testes (8-12 weeks).