Sertoli and Leydig cell numbers and gonadotropin receptors in rat testis from birth to puberty

Transmigration of macrophages through primary adult rat Sertoli cells

The blood testis barrier (BTB) is often studied with isolated immature Sertoli cells (SCs), transepithelial resistance (TER) measurements and FITC dextran diffusion assays. Recently, it was found that even in the absence of SCs, only few immune cells enter the seminiferous tubules. Thus, in this study, we evaluated the testicular immunological barrier (TIB) in vitro by transmigration of macrophages through SCs with and without peritubular cells (PCs) and with or without matrigel (MG). Primary PCs were isolated from adult rat testis and kept in mono- or co-cultures with the conditionally reprogrammed primary adult Sertoli cell line (PASC1) from rat that has been recently generated by our group. Rat monocytes isolated from fresh blood were differentiated into M0 macrophages, and after polarization to M1 or M2 macrophages characterized by gene expression of CXCL11 and TNF-α for M1, or CCL17 and CCL22 for M2. Transmigration of LeukoTracker-labeled M0, M1, and M2 macrophages through mono- and co-cultures of PCs/SCs with and without MG demonstrated that SCs are the main constituent of the TIB in vitro with only a negligible contribution of PCs or MG. Moreover, M2 macrophages showed less migration activity compared to M0 or M1. Treatment of SCs with testosterone (T) showed positive effects on the barrier in contrast to negative effects by interleukin-6 (IL-6) or tumor necrosis factor-α (TNF-α). The new transmigration model is suitable to evaluate transmigration of macrophages through a barrier consisting of testicular cells and can be applied to study the integrity of testicular barriers with respect to immunological aspects.

Follicle-stimulating hormone regulates Notch signalling in the seminiferous epithelium of continuously and seasonally breeding rodents

CONTEXT

Juxtacrine (contact-dependent) communication between the cells of seminiferous epithelium mediated by Notch signalling is of importance for the proper course of spermatogenesis in mammals.

AIMS

The present study was designed to evaluate the role of follicle-stimulating hormone (FSH) in the regulation of Notch signalling in rodent seminiferous epithelium.

METHODS

We explored the effects (1) of pharmacological inhibition of the hypothalamus-pituitary-gonadal (HPG) axis and FSH replacement in pubertal rats, and (2) of photoinhibition of HPG axis followed by FSH substitution in seasonally breeding rodents, bank voles, on Notch pathway activity. Experiments on isolated rat Sertoli cells exposed to FSH were also performed. Gene and protein expressions of Notch pathway components were analysed using RT-qPCR, western blot and immunohistochemistry/immunofluorescence.

KEY RESULTS

Distribution patterns of Notch pathway proteins in bank vole and rat seminiferous epithelium were comparable; however, levels of activated Notch1 and Notch3, hairy/enhancer of split 1 (HES1) and hairy/enhancer of split-related with YRPW motif 1 (HEY1) in bank voles were dependent on the length of the photoperiod. In response to FSH similar changes in these proteins were found in both species, indicating that FSH is a negative regulator of Notch pathway activity in seminiferous epithelium.

CONCLUSIONS

Our results support a common mechanism of FSH action on Notch pathway during onset and recrudescence of spermatogenesis in rodents.

IMPLICATIONS

Interaction between FSH signalling and Notch pathway in Sertoli cells may be involved in spermatogenic activity changes of the testes occurring during puberty or photoperiod shift in continuously and seasonally breeding rodents, respectively.

Sertoli, Leydig, and Spermatogonial Cells’ Specific Gene and Protein Expressions as Dog Testes Evolve from Immature into Mature States

Sertoli, Leydig, and spermatogonial cells proliferate and differentiate from birth to puberty and then stay stable in adulthood. We hypothesized that expressions of spermatogenesis-associated genes are not enhanced with a mere increase of these cells’ numbers. To accept this postulation, we investigated the abundances of Sertoli cell-specific FSHR and AMH, Leydig cell-specific LHR and INSL3, and spermatogonia-specific THY1 and CDH1 markers in immature and mature canine testis. Four biological replicates of immature and mature testes were processed, and RT-PCR was performed to elucidate the cells’ specific markers. The data were analyzed by ANOVA, using the 2−∆∆Ct method to ascertain differences in mRNA expressions. In addition, Western blot and IHC were performed. Gene expressions of all the studied cells’ specific markers were down-regulated (p < 0.05) in adult testis compared with immature testis. Western blot and immunohistochemistry showed the presence of these proteins in the testis. Protein expressions were greater in immature testis compared with mature testis (p < 0.05). Despite the obvious expansion of these cells’ numbers from immature to adult testis, the cells’ specific markers were not enriched in mature testis compared with immature dog testis. The results support the postulation that the gene expressions do not directly correlate with the increase of the cell numbers during post-natal development but changes in gene expressions show functional significance.

Effect of Cryptorchidism on the Histomorphometry, Proliferation, Apoptosis, and Autophagy in Boar Testes

Simple Summary

Body temperature has detrimental effects on sperm quality in mammalian species, including pigs. However, the molecular mechanism of this is not yet well understood. Cryptorchidism is when one or both testes fail to descend into the scrotum, which leads the testes to be exposed to the body temperature. The aims of present study were to investigate the effect of body temperature on the histomorphometry, apoptosis and the expression of the proliferation-associated protein PCNA and the autophagy-associated protein LC3 in spontaneous unilateral cryptorchid boar testes. Our findings showed that cryptorchidism had no evident influence on the number of Sertoli cells in boars. In cryptorchid testes, spermatogonia markedly decreased and the seminiferous tubule contained only a few spermatogonia, but did not contain post-meiotic germ cells. The altered seminiferous epithelium of the cryptorchid testis showed a low proliferation of its spermatogonia, with apoptosis and autophagy like that of scrotal testis, which probably entailed a gradual degeneration of the epithelium and the impossibility of its recovery. Although the number of Sertoli cells did not change, it was likely that their functionality was altered and that this affected the proliferation capacity of spermatogonia, causing the arrest of spermatogenesis.

Abstract

Spontaneous unilateral cryptorchid boars have one testis in the abdomen or inguinal canal, causing its temperature to be at or near the body temperature, which impairs spermatogenesis, although the histomorphometry and molecular mechanisms underlying this process remain unclear. The aim of the present study was to determine the histomorphometry, proliferation, apoptosis, and autophagy alterations in spermatogonia and Sertoli cells in unilateral cryptorchid, scrotal (contrascrotal), and preweaning piglet (preweaning) testes. Histomorphometrical analysis of cryptorchid testes showed that the seminiferous tubules contained only Sertoli cells and a few spermatogonia, but did not contain post-meiotic germ cells. The number of spermatogonia markedly decreased, and the number of Sertoli cells did not change remarkably in cryptorchid testes. TUNEL assay results showed that apoptosis signals were predominantly observed in spermatogonia. In cryptorchid and contrascrotal testes, proliferating cell nuclear antigen (PCNA) and LC3 were located in spermatogonia. The number of PCNA-positive, TUNEL-positive, and LC3-positive germ cells was low, and the protein and mRNA levels of PCNA and LC3 were significantly decreased in cryptorchid testes. Taken together, the number of Sertoli cells did not change remarkably, whereas the number of germ cells decreased in the cryptorchid testes, compared with that in the contrascrotal testes. Insufficient proliferation, excessive apoptosis, and autophagy were involved in the regulation of the decrease in spermatogonia in cryptorchid boar testes.

Suppression of Sertoli cell tumour development during the first wave of spermatogenesis in inhibin α-deficient mice

A dynamic partnership between follicle-stimulating hormone (FSH) and activin is required for normal Sertoli cell development and fertility. Disruptions to this partnership trigger Sertoli cells to deviate from their normal developmental pathway, as observed in inhibin α-knockout (Inha-KO) mice, which feature Sertoli cell tumours in adulthood. Here, we identified the developmental windows by which adult Sertoli cell tumourigenesis is most FSH sensitive. FSH was suppressed for 7 days in Inha-KO mice and wild-type littermates during the 1st, 2nd or 4th week after birth and culled in the 5th week to assess the effect on adult Sertoli cell development. Tumour growth was profoundly reduced in adult Inha-KO mice in response to FSH suppression during Weeks 1 and 2, but not Week 4. Proliferative Sertoli cells were markedly reduced in adult Inha-KO mice following FSH suppression during Weeks 1, 2 or 4, resulting in levels similar to those in wild-type mice, with greatest effect observed at the 2 week time point. Apoptotic Sertoli cells increased in adult Inha-KO mice after FSH suppression during Week 4. In conclusion, acute FSH suppression during the 1st or 2nd week after birth in Inha-KO mice profoundly suppresses Sertoli cell tumour progression, probably by inhibiting proliferation in the adult, with early postnatal Sertoli cells being most sensitive to FSH action.

Effects of dietary omega-3/omega-6 fatty acid ratios on reproduction in the young breeder rooster

Background

Polyunsaturated fatty acids (PUFAs) are necessary for the body's metabolism, growth and development. Although PUFAs play an important role in the regulation of reproduction, their role in testis development in the rooster is unknown. The present study was conducted to investigate the effects of omega-3/omega-6 (n-3/n-6, PUFAs) ratios on reproductive performance in young breeder roosters. Plasma levels of reproductive hormones, testis development, and reproductive hormone receptor and StAR mRNA expression were also assessed.

Results

Although PUFAs (n-3/n-6: 1/4.15) had no significant effect on the testis index (P > 0.05), the spermatogonial development and germ cell layers were increased. Moreover, serum levels of hormones (GnRH, FSH, LH and T) on day 35 were also significantly increased by PUFAs (n-3/n-6: 1/4.15). To investigate whether PUFAs regulate the expression of hormone receptors and StAR, real time-PCR was used to measure GnRHR, FSHR, LHR and StAR mRNA levels. PUFAs significantly increased the mRNA levels of all of these genes.

Conclusions

These results indicate that PUFAs enhance the reproductive performance of young roosters by increasing hormone secretion and function, the latter by up-regulating receptor expression. These findings provide a sound basis for a balanced n-3/n-6 PUFA ratio being beneficial to young rooster reproduction.

The tyrosine phosphatase SHP2 regulates Sertoli cell junction complexes

The blood-testis barrier (BTB) is a large junctional complex composed of tight junctions, adherens junctions, and gap junctions between adjacent Sertoli cells in the seminiferous tubules of the testis. Maintenance of the BTB as well as the controlled disruption and reformation of the barrier is essential for spermatogenesis and male fertility. Tyrosine phosphorylation of BTB proteins is known to regulate the integrity of adherens and tight junctions found at the BTB. SHP2 is a nonreceptor protein tyrosine phosphatase (PTP) and a key regulator of growth factor-mediated tyrosine kinase signaling pathways. We found that SHP2 is localized to Sertoli-Sertoli cell junctions in rat testis. The overexpression of a constitutive active SHP2 mutant, SHP2 Q79R, up-regulated the BTB disruptor ERK1/2 via Src kinase in primary rat Sertoli cells in culture. Furthermore, focal adhesion kinase (FAK), which also supports BTB integrity, was found to interact with SHP2 and constitutive activation of SHP2 decreased FAK tyrosine phosphorylation. Expression of the SHP2 Q79R mutant in primary cultured Sertoli cells also resulted in the loss of tight junction and adherens junction integrity that corresponded with the disruption of the actin cytoskeleton and mislocalization of adherens junction and tight junction proteins N-cadherin, β-catenin, and ZO-1 away from the plasma membrane. These results suggest that SHP2 is a key regulator of BTB integrity and Sertoli cell support of spermatogenesis and fertility.

Alteration of cell membrane proteoglycans impairs FSH receptor/Gs coupling and ERK activation through PP2A-dependent mechanisms in immature rat Sertoli cells

BACKGROUND

During the pre-pubertal life, the cessation of Sertoli cell proliferation and the onset of differentiation are associated with a shift in the FSH-mediated signaling leading to inhibition of the ERK-mitogenic pathway and to a concomitant sensitization of cAMP/PKA pathway.

METHODS

To highlight the role of cell proteoglycans (PGs) in the shift of FSH signaling, both FSH-induced cAMP production and ERK1/2 inactivation were studied in untreated and sodium chlorate PG-depleted cultured Sertoli cells from 20day-old rats.

RESULTS

Depletion of cell membrane PGs by sodium chlorate reduced FSH-, but not cholera toxin-stimulated cAMP production as well as basal ERK phosphorylation through an okadaic acid (OA)-sensitive mechanism. Involvement of PP2A was further substantiated by a marked decrease in membrane- associated PP2A activity under SC conditions and by the OA-induced restoration of PKA-dependent ERK inactivation in SC-treated cells.

CONCLUSIONS

In 20-day-old rat Sertoli cells, transmembrane cell PGs, through tethering/activation of PP2A activity exerts regulatory control on both FSH receptor/Gs coupling and ERK phosphorylation.

GENERAL SIGNIFICANCE

Besides their antiproliferative roles, cell PGs such as syndecan-1, could be involved in the increase in cAMP response to FSH occurring in Sertoli cells at the time of transition between proliferative and differentiated states.

A switch in Sertoli cell responsiveness to FSH may be responsible for robust onset of germ cell differentiation during prepubartal testicular maturation in rats

FSH and Testosterone (T) regulate spermatogenesis via testicular Sertoli cells (Sc), which bear receptors for these hormones. Despite sufficient circulating levels of FSH and T postnatally, predominant appearance of spermatogonia B and spermatocytes is not discernible until 11 and 18 days of postnatal age, respectively, in rat testes. In an attempt to explore the underlying causes, we cultured Sc from neonatal (5- and 9-day-old) and prepubertal (12- and 19-day-old) rat testes and compared the status of FSH receptor (FSH-R) and androgen receptor (AR) signaling. Protein and mRNA levels of FSH-R and AR remained uniform in cultured Sc from all age groups. Androgen binding ability of AR was similar, and T-induced nuclear localization of AR was discernible in Sc from all age groups. Binding of FSH to FSH-R, subsequent production of cAMP, and mRNA of stem cell factor (SCF) and glial cell line-derived neurotrophic factor (GDNF), known to be essential for the robust differentiation of repopulating spermatogonia, were significantly augmented in prepubertal Sc compared with those in neonatal Sc. However, treatment of neonatal Sc with cholera toxin or forskolin, which stimulate cAMP production bypassing FSH-R, demonstrated a concomitant rise in SCF and GDNF mRNA expression, which was similar to the FSH-mediated rise observed in prepubertal Sc. These observations suggested that, during prepubertal Sc maturation, the ability of FSH-R to respond to FSH is significantly augmented and is associated with the robust differentiation of repopulating spermatogonia, and such a switch in Sc from FSH-resistant to FSH-responsive mode during prepubertal development may underlie the initiation of robust spermatogenesis.

Differentiation of umbilical cord mesenchymal stem cells into steroidogenic cells in comparison to bone marrow mesenchymal stem cells

OBJECTIVES

Human umbilical cord can be obtained easily and it represents a non-controversial source of mesenchymal stem cells (MSCs) and umbilical cord Wharton's jelly-derived MSCs (UC-MSCs) have low immunogenicity. In this study, UC-MSCs were induced to become steroidogenic cells and compared to bone marrow-derived MSCs (BM-MSCs).

MATERIAL AND METHODS

UC-MSCs and BM-MSCs were induced to differentiate into steroidogenic cells by infection with adenovirus containing SF-1. Expression of steroidogenic mRNA was analysed by real-time RT-PCR and steroid secretion was detected by ELISA testing. Viability of differentiated cells was examined using cell counting kit-8 assay.

RESULTS

Both UC-MSCs and BM-MSCs expressed typical MSC markers and could differentiate into adipocytes, osteocytes and chondrocytes and both cell types had the potential to differentiate into steroidogenic cells after being infected with adenovirus containing SF-1 cDNA. However, UC-MSCs had significantly higher proliferative potential than BM-MSCs and differentiated UC-MSCs had significantly higher expression of all steroidogenic mRNAs tested over those of differentiated BM-MSCs; this included P450 side-chain cleavage enzyme, 3β-HSD, 17β-HSD type 3, LH-R, ACTH-R, P450c21 and CYP17. In addition, differentiated UC-MSCs secreted significantly more steroidogenic hormones than differentiated BM-MSCs, including testosterone and cortisol. Furthermore, differentiated UC-MSCs had significantly higher cell viability than differentiated BM-MSCs.

CONCLUSIONS

UC-MSCs had significantly higher potential of steroidogenic differentiation than BM-MSCs; thus, UC-MSCs could be favourable cells of choice for cell-based therapy for steroidogenic insufficiency compared to BM-MSCs.

Upstream stimulatory factor induces Nr5a1 and Shbg gene expression during the onset of rat Sertoli cell differentiation

Within the testis, each Sertoli cell can support a finite number of developing germ cells. During development, the cessation of Sertoli cell proliferation and the onset of differentiation establish the final number of Sertoli cells and, thus, the total number of sperm that can be produced. The upstream stimulatory factors 1 and 2 (USF1 and USF2, respectively) differentially regulate numerous Sertoli cell genes during differentiation. To identify genes that are activated by USF proteins during differentiation, studies were conducted in Sertoli cells isolated from 5- and 11-day-old rats, representing proliferating and differentiating cells, respectively. Usf1 mRNA and USF1 protein levels were increased between 5 and 11 days after birth. In vitro studies revealed that USF1 and USF2 DNA-binding activity also increased at 11 days for the promoters of four potential target genes, Fshr, Gata4, Nr5a1, and Shbg. Chromatin immunoprecipitation assays confirmed that USF recruitment increased in vivo between 5 and 11 days after birth at the Fshr, Gata4, and Nr5a1 promoters. Expression of Nr5a1 and Shbg, but not of Fshr or Gata4, mRNAs was elevated in 11-day-old Sertoli cells compared with 5-day-old Sertoli cells. Transient transfection of USF1 and USF2 expression vectors up-regulated Nr5a1 and Shbg promoter activity. RNA interference assays demonstrated that USF1 and USF2 contribute to Nr5a1 and Shbg expression in differentiating cells. Together, these data indicate that increased USF levels induce the expression of Nr5a1 and Shbg during the differentiation of Sertoli cells, whereas Fshr and Gata4 expression is not altered by USF proteins during differentiation.

Regulation of Sertoli-germ cell adhesion and sperm release by FSH and nonclassical testosterone signaling

Testosterone and FSH act in synergy to produce the factors required to maximize the production of spermatozoa and male fertility. However, the molecular mechanisms by which these hormones support spermatogenesis are not well established. Recently, we identified a nonclassical mechanism of testosterone signaling in cultured rat Sertoli cells. We found that testosterone binding to the androgen receptor recruits and activates Src tyrosine kinase. Src then causes the activation of the epidermal growth factor receptor, which results in the phosphorylation and activation of the ERK MAPK and the cAMP response element-binding protein transcription factor. In this report, we find that FSH inhibits testosterone-mediated activation of ERK and the MAPK pathway in Sertoli cells via the protein kinase A-mediated inhibition of Raf kinase. In addition, FSH, as well as inhibitors of Src and ERK kinase activity, reduced germ cell attachment to Sertoli cells in culture. Using pathway-specific androgen receptor mutants we found that the nonclassical pathway is required for testosterone-mediated increases in germ cell attachment to Sertoli cells. Studies of seminiferous tubule explants determined that Src kinase, but not ERK kinase, activity is required for the release of sperm from seminiferous tubule explants. These findings suggest the nonclassical testosterone-signaling pathway acts via Src and ERK kinases to facilitate the adhesion of immature germ cells to Sertoli cells and through Src to permit the release of mature spermatozoa. In contrast, FSH acts to limit testosterone-mediated ERK kinase activity and germ cell attachment.

Developmental regulation of p70 S6 kinase by a G protein-coupled receptor dynamically modelized in primary cells

The mechanisms whereby G protein-coupled receptors (GPCR) activate signalling pathways involved in mRNA translation are ill-defined, in contrast to tyrosine kinase receptors (TKR). We compared a GPCR and a TKR, both endogenously expressed, for their ability to mediate phosphorylation of 70-kDa ribosomal S6 kinase p70S6K in primary rat Sertoli cells at two developmental stages. In proliferating cells stimulated with follicle-stimulating hormone (FSH), active p70S6K was phosphorylated on T389 and T421/S424, through cAMP-dependent kinase (PKA) and phosphatidyl-inositide-3 kinase (PI3K) antagonizing actions. In FSH-stimulated differentiating cells, active p70S6K was phosphorylated solely on T389, PKA and PI3K independently enhancing its activity. At both developmental stages, insulin-induced p70S6K regulation was consistent with reported data. Therefore, TKR and GPCR trigger distinct p70S6K active conformations. p70S6K developmental regulation was formalized in a dynamic mathematical model fitting the data, which led to experimentally inaccessible predictions on p70S6K phosphorylation rate.

USF1/2 transcription factor DNA-binding activity is induced during rat Sertoli cell differentiation

Each Sertoli cell can support a finite number of developing germ cells. During development of the testis, the cessation of Sertoli cell proliferation and the onset of differentiation determine the final number of Sertoli cells and, hence, the number of sperm that can be produced. We hypothesize that the transition from proliferation to differentiation is facilitated by E-box transcription factors that induce the expression of differentiation-promoting genes. The relative activities of E-box proteins were studied in primary Sertoli cells isolated from 5-, 11-, and 20-day-old rats, representing proliferating, differentiating, and differentiated cells, respectively. E-box DNA-binding activity is almost undetectable 5 days after birth but peaks with initiation of differentiation 11 days after birth and remains elevated. Upstream stimulatory factors 1 and 2 (USF1 and USF2) were found to be the predominant E-box proteins present within DNA-protein complexes formed after incubating E-box-containing probes with nuclear extracts from developing Sertoli cells. The known potentiator of Sertoli cell differentiation, thyroxine, increases USF DNA-binding activity in Sertoli cells before differentiation (5-day-old Sertoli cells) but not after differentiation is initiated (11- and 20-day-old Sertoli cells). The developmental-specific increase in USF1 and USF2 DNA-binding activity may facilitate the switch from proliferation to differentiation and, thus, determine the ultimate number of Sertoli cells present within the testes and the upper limit of fertility.

Expression of the cAMP-phosphodiesterase PDE4D isoforms and age-related changes in follicle-stimulating hormone-stimulated PDE4 activities in immature rat sertoli cells

Major changes in the cAMP-dependent signal transduction pathway triggered by FSH take place during transition of rat Sertoli cells from proliferative to the quiescent/terminally differentiated state. Using Sertoli cell cultures isolated from 10-, 20-, and 30-day-old rats, we recorded a specific increase in PDE4 activity in both the soluble and particulate subcellular fractions of 20-day-old Sertoli cells, which also displayed the highest cAMP response to FSH and the highest FSH-induced increase in PDE4 activity in both subcellular compartments. RT-PCR and immunoblotting experiments showed that almost all the PDE4D isoforms, known as the main cAMP-regulated rolipram-sensitive PDE in Sertoli cells, were expressed throughout the early postpartum period, whereas only the short PDE4D isoforms (PDE4D1 and PDE4D2) were transcriptionally regulated by FSH. Unexpectedly, the immunoblot data also revealed that the soluble PDE4 activities were mainly related to the long PDE4D isoforms and that short PDE4D1 was predominantly particulate. The subcellular distribution and expression of PDE4D proteins were unaffected by the developmental status of the Sertoli cells. Only the expression of short PDE4D1 appeared to be upregulated by FSH and only in 20-day-old Sertoli cells, which suggests phenotype-dependent differential regulation of Pde4d1 mRNA translation. Resensitization of the cAMP response to FSH in 20-day-old Sertoli cells was also associated with the highest FSH-induced transient increase in both soluble and particulate PDE4 activities, which suggests developmental changes in the PKA-mediated upregulation of the catalytic activities of long PDE4D. Such alterations may be involved in the phenotype-dependent alterations in FSH receptor coupling with its associated G proteins in rat Sertoli cells.

Early influences on the tempo of puberty

Fetal growth retardation appears to be associated with an increased risk of premature adrenarche, early puberty, polycystic ovary syndrome and associated fertility problems. In a rat model of intrauterine growth retardation, based on ligation of the uterine arteries, the onset of puberty was delayed in female pups, with anovulation during the first cycle. The ovaries showed a lower number of follicles. The onset of puberty was also delayed in male pups. Testosterone production was lower in these growth-retarded rats compared with controls. The relationship between birth weight and the onset of puberty and pubertal progression in different cohorts of healthy children has been examined. In girls, no differences were observed in timing and progression of puberty, including age of menarche, between groups of different birth weights. In boys, a relatively delayed onset of puberty was observed in those with low birth weight, with a normally timed progression. In children with low birth weight, particularly boys, higher dehydroepiandrosterone levels were found compared with children with a normal birth weight, indicating an overactive adrenal gland in children with low birth weight. These data indicate that impaired fetal growth may have long-lasting effects on pubertal development. The fact that results of human studies on the relationship between fetal growth and the onset of puberty are often controversial may be explained by the heterogeneity of children born small for gestational age with respect to the intrauterine insult that they experience. From rat studies, it is clear that a serious intrauterine insult associated with growth failure can lead to dysregulation of puberty and gonadal function.

FSH and testosterone signaling in Sertoli cells

Testosterone and follicle-stimulating hormone (FSH) are required to obtain full reproductive potential. In the testis, somatic Sertoli cells transduce signals from testosterone and FSH into the production of factors that are required by germ cells as they mature into spermatozoa. Recent advances in identifying new signaling pathways that are regulated by FSH and testosterone have allowed for refinement in the understanding of the independent, overlapping and synergistic actions of these hormones. In this review, we discuss the signaling pathways that are regulated by FSH and testosterone as well as the resulting metabolic and gene expression changes that occur as related to Sertoli cell proliferation, differentiation and the support of spermatogenesis.

Cell biology of Leydig cells in the testis

This article reviews results on differentiation, structure, and regulation of Leydig cells in the testes of rodents and men. Two different populations-fetal and adult Leydig cells-can be recognized in rodents. The cells in these two populations are different in ultrastructure, life span, capacity for androgen synthesis, and mechanisms of regulation. A brief survey on the origin, ontogenesis, characterization of precursors, ultrastructure, and functional markers of fetal and adult Leydig cells is presented, followed by an analysis of genes in Leydig cells and the role of luteinizing hormone and its receptor, steroidogenic acute regulatory protein, hydroxysteroid dehydrogenases, androgen and its receptor, anti-Müllerian hormone, estrogens, and thyroid hormones. Various growth factors modulate Leydig cell differentiation, regeneration, and steroidogenic capacity, for example, interleukin 1alpha, transforming growth factor beta, inhibin, insulin-like growth factors I and II, vascular endothelial growth factor, and relaxin-like growth factor. Retinol and retinoic acid increase basal testosterone secretion in adult Leydig cells, but decrease it in fetal Leydig cells. Resident macrophages in the interstitial tissue of the testis are important for differentiation and function of Leydig cells. Apoptosis of Leydig cells is involved in the regulation of Leydig cell number and can be induced by cytotoxins. Characteristics of aging Leydig cells in rodents seem to be species specific. 11beta-hydroxysteroid dehydrogenase protects testosterone synthesis in the Leydig cells of stressed rats. Last, the following aspects of human Leydig cells are briefly described: origin, differentiation, triphasic development, aging changes, pathological changes, and gene mutations leading to infertility.

Stem cell and niche development in the postnatal rat testis

Adult tissue stem cells self-renew and differentiate in a way that exactly meets the biological demand of the dependent tissue. We evaluated spermatogonial stem cell (SSC) activity in the developing rat testis and the quality and accessibility of the stem cell niche in wild type, and two busulfan-treated models of rat pup recipient testes using an SSC transplantation technique as a functional assay. While our results revealed a 69-fold increase in stem cell activity during rat testis development from neonate to adult, only moderate changes in SSC concentration were observed, and stem cells from neonate, pup, and adult donor testes produce spermatogenic colonies of similar size. Analysis of the stem cell niche in recipient rat testes demonstrated that pup testes support high levels of donor stem cell engraftment when endogenous germ cells are removed or compromised by busulfan treatment. Fertility was established when rat pup donor testis cells were transplanted into fetal- or pup-busulfan-treated recipient rat pup testes, and the donor genotype was transmitted to subsequent generations. These results provide insight into stem cell/niche interactions in the rat testis and demonstrate that techniques originally developed in mice can be extended to other species for regenerative medicine and germline modification.

Effects of melatonin on Leydig cells in pinealectomized rat: an immunohistochemical study

We have investigated immunohistochemically the effects of melatonin on Leydig cells in rat. Three groups of Wistar rats were used. Rats in group I and II were sham-pinealectomized (control) and pinealectomized, respectively, whereas rats in group III were pinealectomized and injected daily with melatonin for 2 months. At the end of the experiment, all animals were killed by decapitation and blood samples were obtained. Serum testosterone levels were determined with the use of a chemiluminescent enzyme immunoassay. Testicular tissue was collected and processed for semiquantitative evaluation of immunohistochemical testosterone staining. Intensity of immunostaining was determined on a scale between 0 (no staining) and 5 (heavy staining). In pinealectomized rats, serum testosterone levels were significantly increased as compared to sham-pinealectomized rats. Daily administration of melatonin after pinealectomy resulted in significant decreased serum testosterone levels as compared to levels in control and pinealectomized rats. Immunostaining of testosterone was moderate (3+) in sham-pinealectomized rats, heavy (5+) in pinealectomized rats and low (1+) in pinealectomized rats that were treated with melatonin, respectively. The results of our study indicate that pinealectomy induces increased testosterone secretion in Leydig cells and this increased secretion can be prevented by administration of melatonin.

Differentiation of the adult Leydig cell population in the postnatal testis

Five main cell types are present in the Leydig cell lineage, namely the mesenchymal precursor cells, progenitor cells, newly formed adult Leydig cells, immature Leydig cells, and mature Leydig cells. Peritubular mesenchymal cells are the precursors to Leydig cells at the onset of Leydig cell differentiation in the prepubertal rat as well as in the adult rat during repopulation of the testis interstitium after ethane dimethane sulfonate (EDS) treatment. Leydig cell differentiation cannot be viewed as a simple process with two distinct phases as previously reported, simply because precursor cell differentiation and Leydig cell mitosis occur concurrently. During development, mesenchymal and Leydig cell numbers increase linearly with an approximate ratio of 1:2, respectively. The onset of precursor cell differentiation into progenitor cells is independent of LH; however, LH is essential for the later stages in the Leydig cell lineage to induce cell proliferation, hypertrophy, and establish the full organelle complement required for the steroidogenic function. Testosterone and estrogen are inhibitory to the onset of precursor cell differentiation, and these hormones produced by the mature Leydig cells may be of importance to inhibit further differentiation of precursor cells to Leydig cells in the adult testis to maintain a constant number of Leydig cells. Once the progenitor cells are formed, androgens are essential for the progenitor cells to differentiate into mature adult Leydig cells. Although early studies have suggested that FSH is required for the differentiation of Leydig cells, more recent studies have shown that FSH is not required in this process. Anti-Müllerian hormone has been suggested as a negative regulator in Leydig cell differentiation, and this concept needs to be further explored to confirm its validity. Insulin-like growth factor I (IGF-I) induces proliferation of immature Leydig cells and is associated with the promotion of the maturation of the immature Leydig cells into mature adult Leydig cells. Transforming growth factor alpha (TGFalpha) is a mitogen for mesenchymal precursor cells. Moreover, both TGFalpha and TGFbeta (to a lesser extent than TGFalpha) stimulate mitosis in Leydig cells in the presence of LH (or hCG). Platelet-derived growth factor-A is an essential factor for the differentiation of adult Leydig cells; however, details of its participation are still not known. Some cytokines secreted by the testicular macrophages are mitogenic to Leydig cells. Moreover, retarded or absence of Leydig cell development has been observed in experimental models with impaired macrophage function. Thyroid hormone is critical to trigger the onset of mesenchymal precursor cell differentiation into Leydig progenitor cells, proliferation of mesenchymal precursors, acceleration of the differentiation of mesenchymal cells into Leydig cell progenitors, and enhance the proliferation of newly formed Leydig cells in the neonatal and EDS-treated adult rat testes.

Differential effect of hyperthyroidism on rat epididymal glycosidases

The impact of hyperthyroidism on epididymal glycosidases was studied in albino rats. Hyperthyroidism was induced in Wistar rats aged 30 days by daily injection of T4 (25 microg/100 g body weight/day intramuscularly) for 30 or 60 days; control rats were injected with vehicle (alkaline saline, pH 7.8). One set of hyperthyroid rats was reverted to euthyroid status by withdrawing T4 treatment after 30 days of hyperthyroidism. To asses the direct effect of thyroid hormone on epididymal hexosaminidases, caput, corpus and cauda tissues were stimulated with 25, 50 or 100 ng/mL T3 for 24 h, after an initial culture of 24 h. The activity of beta-glucosidase decreased in caput, corpus and cauda epididymis of hyperthyroid rats. beta-Galactosidase activity increased in the caput epididymis irrespective of the duration of hyperthyroidism. While a similar decrease occurred in the corpus and cauda epididymis in the 30 day hyperthyroid group, an opposite trend was observed in 60 day hyperthyroid rats. Caput beta-N-acetylglucosaminidase activities increased at both time points, whereas activity decreased in the corpus and cauda in 30 day, but increased in 60 day hyperthyroid rats. Hyperthyroidism consistently increased caput and corpus beta-N-acetylgalactosaminidase activity irrespective of the duration. Cauda epididymal beta-N-acetylgalactosaminidase activity was decreased in 30 day and increased in 60 day hyperthyroid rats. Hyperthyroidism induced changes in caput beta-galactosidase, beta-N-acetylgalactosaminidases, corpus beta-N-acetylglucosaminidase and cauda beta-N-acetylgalactosaminidase which were irreversible while the remaining actvities were brought back to normal when T4 treatment was withdrawn. In vitro studies showed that T3 stimulates epididymal hexosaminidases (beta-N-acetylglucosaminidase and beta-N-acetylgalactosaminidase) irrespective of the dose. These data suggest that thyroid hormones have a specific and direct influence on glycosidases in specific regions of the epididymis.

Impact of neonatal onset hypothyroidism on Sertoli cell number, plasma and testicular interstitial fluid androgen binding protein concentration

The impact of neonatal onset hypothyroidism from day 1 postpartum through different postnatal developmental events on rat testis was studied in vivo. Hypothyroidism was induced in neonates by feeding the lactating mother or directly with 0.05% methimazole (MMI) through drinking water from the day of birth and were killed at day 10, 15, 30, 40 and 60 postpartum. Hypothyroidism was confirmed by radioimmunoassay of thyroid hormones and TSH. Sertoli cell number, plasma and testicular interstitial fluid (TIF) androgen binding protein (ABP) concentration was quantified. Sertoli cell number was consistently decreased in all hypothyroid rats. Plasma ABP was also decreased irrespective of the duration of hypothyroidism. Unlike plasma ABP, TIF ABP concentration in hypothyroid rats increased at day 10, and 15 postpartum and decreased in other age groups. Plasma FSH level was increased significantly in all hypothyroid groups. The present investigation points out that suppression of T3 during the critical period of Sertoli cell proliferation affects their number and functional activity.

Duration-dependent effect of transient neonatal hypothyroidism on sertoli and germ cell number, and plasma and testicular interstitial fluid androgen binding protein concentration

The impact of transient neonatal hypothyroidism on growth and function of puberal testis during different milestones of postnatal testicular development was studied in Wistar rats. Rat pups were made hypothyroid for 10, 15, 30, 40 and 60 days of postnatal age from birth by providing 0.05% (W/V) methimazole (MMI) in the drinking water of the mother, from day 1 postpartum till weaning (25 days postpartum) and thereafter in the drinking water. Control rats were raised without MMI treatment. Sertoli cell number and its function was assessed on day 60 postpartum. Sertoli cell number increased consistently in 10, 15, 30 and 40 days transient hypothyroid rats but decreased in rats subjected to continuous hypothyroidism from birth to 60 days postpartum. Rats subjected to continuous hypothyroidism from birth showed spermatogenic arrest at puberty and had only a single layer of spermatogonia. Transient neonatal hypothyroidism for 10 (or) 15 days from birth increased spermatocytes (pachytene and zygotene), spermatids (elongated and round) whereas, that of 30 and 40 days decreases the number of germ cells. Plasma androgen binding protein (ABP) concentration decreased in puberal rats belonging to all groups, whereas the testicular interstitial fluid (TIF) concentration of ABP increased significantly in 10 and 15 days hypothyroid rats while it decreased in all other groups. These findings indicate that the mitogenic activity of Sertoli cell is increased irrespective of the duration of transient neonatal hypothyroidism. However, the functional activity of Sertoli cells (ABP production) in these puberal rats varies depending upon the postnatal period at which the animals were in hypothyroid state.

Influence of age and photoperiod on steroidogenic function of the testis in the golden hamster

The golden (Syrian) hamster is a seasonal breeder, and exposure of adult animals to short days results in severe gonadal regression with morphological features that resemble the immature testis. The purpose of this study was to investigate testicular steroidogenic capacity in the golden hamster and to analyse the influence of age and photoperiod on this process. Hamsters aged 36 days were maintained on a long photoperiod (14L:10D), and adult animals were then exposed to a long or a short photoperiod (6L:18D) for 14 weeks (the period of time required to achieve maximal gonadal regression), to assess circulating levels and in vitro production of testosterone, dihydrotestosterone and androstane-3 alpha, 17 beta-diol. In peripubertal hamsters, androstane-3 alpha, 17 beta-diol was the main circulating androgen detected, whereas in active adult animals, testosterone showed the highest serum levels. In hamsters exposed to a short photoperiod, blood testosterone levels were significantly lower than levels in adult hamsters exposed to a long photoperiod. Exposure of adult hamsters to a short photoperiod produced a marked reduction in serum concentrations of dihydrotestosterone and androstane-3 alpha, 17 beta-diol, which was not accompanied by a decrease in testicular 5 alpha-reductase activity. In the in vitro experiments, active adult testes were less sensitive than inactive adult testes to stimulation of androgen production with hCG, but showed similar sensitivity to the gonads from hamsters aged 36 days. In accordance with circulating androgen concentrations, the principal androgens produced in the in vitro assays from peripubertal and normal adult testes were androstane-3 alpha, 17 beta-diol and testosterone, respectively. Unexpectedly, the main androgen produced from regressed testes under in vitro conditions was androstane-3 alpha, 17 beta-diol. Inactive gonads released more androstane-3 alpha, 17 beta-diol than did normal adult testes and total in vitro androgen production (testosterone + dihydrotestosterone + androstane-3 alpha, 17 beta-diol) from adult testes was not diminished by exposure to a short photoperiod. However, in spite of the significant increase detected in production of androstane-3 alpha, 17 beta-diol in vitro from regressed testes, inactive gonads produced less androstane-3 alpha, 17 beta-diol than did peripubertal testes. In summary, our studies suggest that testicular androgen biosynthetic capacity in adult hamsters exposed to short photoperiod is not reduced and these regressed testes represent an intermediate physiological state between peripubertal and active adult testes. The significant decrease detected in serum androgen concentrations during the involution phase could result from the absence of stimulating pituitary factors, together with a negative regulation of steroidogenesis by different non-steroidal signals originating within and/or outside of the testis.

Stable transfection of the rat follicle-stimulating hormone receptor complementary DNA into an immortalized murine Sertoli cell line

A plasmid expressing the rat FSH receptor (R) cDNA under the Simian virus (SV) 40 promoter/enhancer was stably transfected into a mouse Sertoli cell (SC) line (MSC-1) established from transgenic mice carrying a fusion gene of the human anti-Müllerian hormone (AMH) promoter sequences linked to the SV40 T-antigen gene (Peschon et al., 1992). The original cell line has numerous SC characteristics, but it was reported not to express the inhibin-alpha and follicle-stimulating hormone (FSH)R genes. The new FSHR expressing cell line possessed approximately 2000 per cell with equilibrium association constant (Ka) of 1.5 x 10(9) l/mol. In Northern blots, an FSHR mRNA species of 2.6 kb was found. The cells responded to recombinant human FSH (recFSH) and pertussis toxin (PT) with stimulated cAMP production. Moreover, PT enhanced the FSH-stimulated cAMP production in these cells, indicating the presence of a functional Gi protein. 12-O-tetradecanoylphorbol-13-acetate (TPA) suppressed the FSH-stimulated cAMP production of the cells, which effect was similar to that observed previously upon protein kinase C (PKC) activation in rat seminiferous tubules in vitro. Hence, the FSHR signalling, and its modulatory pathways, were intact in the FSHR expressing MSC-1 cell line. RT-PCR with inhibin-alpha specific oligonucleotide primers. followed by Southern hybridization, indicated that, unlike previously shown, the original and the FSHR expressing MSC-1 cells do express the inhibin alpha gene. FSH stimulation of the cells decreased their proliferation and, unexpectedly, the inhibin-alpha mRNA levels. The cells have functional features both from neonatal and mature SC. A feature of the former cells is the lack of FSH-stimulated up-regulation of inhibin-alpha expression; in fact FSH decreased this message. The antiproliferative, and apparently differentiating, effect of FSH on these cells resembled mature SC functions. Since adult SC do not proliferate in vitro, the new FSHR expressing and proliferating cell line provides a useful in vitro model for studying some facets of SC functions, though keeping in mind that these transformed cells do not behave identically with adult SC in vivo. The constitutive expression of FSHR in these cells allows the study of posttranscriptional events in the FSHR regulation.

A quantitative morphological study of age-related changes in the donkey testis in the period between puberty and senium

The testis of the donkey was used as a model to study age-related changes in the period between puberty and senium. From the age of 1.5 years to the middle of sexual maturity (5 to 6 years) a number of histophysiological features, all indicative of the spermatogenetic efficiency, increase continuously. Then without a longer-lasting plateau of maximal performance these features undergo continuous retrogression. Thus, the adult testis is an organ in permanent change. During its progressive period (1.5 to 5 years) the average testicular and tubular volumes treble. The increase in tubular volume is due to an increase in tubular length (from 700 m to 1600 m per testis) and tubular diameter (from 205 microns to 250 microns). Parallel to this growth, the spermatogenetic efficiency of the seminiferous epithelium rises: the number of germ cells entering meiosis increases and the cell loss by apoptosis or exfoliation decreases. During the following regressive period of the testis (5-10 years) seminiferous epithelial height and tubular diameter are again gradually reduced to 70 microns and 205 microns, respectively. The absolute number of Sertoli cells per testis decreases continuously from puberty onwards. The tubular lamina propria thickens with advancing age and at the age of 10 years, displays long irregular projections into the seminiferous epithelium.

Neonatal hypothyroidism causes delayed Sertoli cell maturation in rats treated with propylthiouracil: evidence that the Sertoli cell controls testis growth

BACKGROUND

The testes of rats treated neonatally with propylthiouracil (PTU) grow to almost twice their normal size. The cause of testicular enlargement has been suggested to be the result of delayed maturation of Sertoli cells, allowing Sertoli cell division to occur beyond the 15th postnatal day, the commonly recognized cutoff date for Sertoli cell divisions. It has been shown that an increased population of Sertoli cells in postnatal development supports increased numbers of germ cells in adult animals. After examining developing rats treated neonatally with PTU, we hypothesized that an approximate 10-day delay in maturation was occurring and proceeded to test this hypothesis experimentally. Thus the purpose of this report was to determine if a 10-day delay in maturation could explain the increased numbers of Sertoli cells and increased testis size in PTU-treated animals.

METHODS

Both control animals and animals treated neonatally with PTU N = 5/group were sacrificed at 15 and 25 days of age and prepared for electron microscopy.

RESULTS

Micrographs show and morphometric ultrastructural analysis of numerous parameters demonstrated at the 95% probability level that Sertoli cells from 25-day-old PTU animals are not different in size and most constituents (volume and surface area) from 15-day-old control animals and are less mature than 25-day-old control animals. Mitosis of Sertoli cells was observed in PTU-treated animals in 25-day-old animals but not in age-matched controls. The number of Sertoli cells in 25-day-old PTU-treated animals is significantly increased over age-matched controls. Micrographs show the presence of immature Sertoli cell nuclei in 25-day-old animals receiving PTU as well as increased germ cell degeneration in this group. Sertoli cell tight junction formation is also delayed in PTU-treated animals as compared with controls.

CONCLUSIONS

Together, the data show that delayed maturation of Sertoli cells occurs in treated animals that corresponds to a minimum of 10 developmental days. In the immature state, Sertoli cells continue to divide. Data presented herein and published data related to PTU treatment indicate that delayed maturation of the Sertoli cell results in delayed maturation and proliferation of other testicular cell types. From this and from published data, the hypothesis is presented that the Sertoli cell is responsible for the overall control of testis development.

Building a testis

Specific cellular, subcellular and acellular components of the rat testis including the capsule, the peritubular tissue (tunica propria) and the lymphatic endothelium were analyzed using morphometric techniques at cellular and subcellular levels to yield volume and surface area data. These data were integrated with previously published data for other cellular components of the rat testis to provide information about the volumetric composition for virtually every component of this organ. For major cell types (Leydig, Sertoli, myoid cells and germ cells) the data are expressed to the subcellular level in terms of volume and, in some instances, surface area. Graphic portrayals of testis constituents are used for rapid visual understanding of testis structure. The data presented herein are useful in conjunction with biochemical data to describe physiological properties of cells and cell components and also for understanding how structure differs under experimental and in pathological situations.

Characteristics of mitotic cells in developing and adult testes with observations on cell lineages

This report describes characteristics of dividing cells, primarily in developing (10-40 day) rat testis and relates the structure of the dividing cells to the structure of interphase cells. Mitotic cells were characterized in seven zones. Dividing Sertoli cells were seen prior to day 15 and possessed distinct characteristics as compared with dividing germ cells. Myoid cells showed morphological characteristics of precursor myoid cells; 'clear cells' self-replicated in the myoid cell layer; adult-type Leydig cells, some containing lipid, differentiated early (10th-15th postnatal days) from fibroblast-like cells of the multilayered tubule wall and later (15th-25th postnatal days) from dividing differentiated and semi-differentiated Leydig cells within the lymphatic space; fibroblastic cells arose from cells with similar morphological characteristics; semi-differentiated Leydig cells divided, and differentiated Leydig cells in the lymphatic space self-renewed; undifferentiated perivascular cells most likely gave rise to Leydig cells, pericytes; arteriolar smooth muscle cells and vascular endothelial cells arose from division of the pre-existing respective cell types. Fetal Leydig cells appeared to remain but, with time, they appeared to lose their lipid. The data suggest that (1) early recruitment of Leydig cells from undifferentiated peritubular fibroblast-like cells, (2) later mitosis of differentiated and semi-differentiated Leydig cells primarily in the interstitium but also in the perivascular region, and (3) the continued presence of pre-existing Leydig cells from the fetus constitute the adult population. Leydig cell division in the adult mouse was documented. This study provides the necessary information for the recognition of cell divisions to study of cell lineages among testis cells.

Mammalian follicle-stimulating hormone stimulates DNA synthesis in secondary spermatogonia and Sertoli cells in organ culture of testes fragments from the newt, Cynops pyrrhogaster

We previously showed in organ culture of testes fragments from Cynops pyrrhogaster that mammalian follicle-stimulating hormone (FSH) stimulates secondary spermatogonia to differentiate into primary spermatocytes. In this report, we demonstrate in organ culture that FSH stimulates DNA synthesis in secondary spermatogonia and Sertoli cells: the numbers of secondary spermatogonia and Sertoli cells incorporating 5-bromo-2'-deoxyuridine (BrdU) throughout the culture period in the presence of FSH were 3-5 times those incorporating BrdU in the absence of FSH. Moreover, addition of FSH to testes fragments which had become quiescent after a week of culture in the absence of FSH, induced after a day a remarkable increase in the number of spermatogonia and Sertoli cells incorporating BrdU. The above results indicate that FSH stimulates and induces DNA synthesis in spermatogonia and Sertoli cells. Most of the spermatogonia within a cyst were labelled simultaneously and at the same density, indicating that they underwent synchronous DNA synthesis, whereas all the Sertoli cells within a cyst were not labelled simultaneously, indicating that they synthesised DNA asynchronously. When testes fragments pulse-labelled with BrdU were cultured in FSH for 14 days, the secondary spermatogonia differentiated into primary spermatocytes, whereas in the absence of FSH they failed to differentiate and most died by the 7th day. The above results together show that FSH is required for the proliferation of both secondary spermatogonia and Sertoli cells as well as the differentiation of secondary spermatogonia into primary spermatocytes.

Testosterone immunoexpression in human Leydig cells of the tunica albuginea testis and spermatic cord. A quantitative study in normal foetuses, young adults, elderly men and patients with cryptorchidism

A semi-quantitative study of the extra-parenchymal Leydig cells in the tunica albuginea testis and spermatic cord was performed on histological sections immunostained with anti-testosterone antibodies in the testes and spermatic cords obtained from human foetuses, adults and elderly men without testicular or related diseases (autopsy specimens), as well as from adult men with cryptorchidism (surgical specimens). The albugineal Leydig cells appeared in small groups in the vicinity of blood vessels. The Leydig cells of the spermatic cord usually appeared inside or around nerve trunks. The percentages of testes and spermatic cords with extra-parenchymal Leydig cells were higher in the cryptorchid testis group than in the normal male groups. The number of Leydig cells per mm2 in the tunica albuginea testis was higher in normal adult males than in foetuses. This number decreased in elderly men and increased markedly in cryptorchidism. The number of Leydig cells per mm2 in the spermatic cord was also higher in normal adults than in foetuses and it did not change with either advancing age or cryptorchidism. In foetuses, the percentage of cells intensely immunostained by anti-testosterone antibodies in the tunica albuginea and spermatic cord did not differ significantly from that found in the testicular parenchyma, whereas in the other three groups (adult, elderly, and cryptorchid men) the percentages of these cells in the tunica albuginea and spermatic cord were significantly lower than in the testicular parenchyma.

Changes in lectin binding patterns of Leydig cells during fetal and postnatal development in mice

Changes in the lectin binding of mouse Leydig cells during fetal and postnatal development were examined by light- and electron-microscopy using eight different biotinylated lectins (ConA, WGA, RCA-I, UEA-I, GS-I, PNA, SBA and GS-II). At the light-microscopic level, ConA, WGA, RCA-I, UEA-I and GS-I showed the same binding pattern in which all five lectins bound to the plasma membrane and cytoplasm of Leydig cells from the 13th day post coitum (p.c.) to the 8th postnatal week. PNA, SBA and GS-II reactions were positive in the plasma membrane and cytoplasm of Leydig cells from the 13th day p.c. to 15th day post partum (p.p.) but disappeared completely by day 20. At the electron-microscopic level, gold particles representing the GS-I or GS-II binding sites were distributed primarily along the cell surface membrane, including that of microvilli, as well as in the cytoplasm. These results indicate that certain glycoconjugates bearing D-galactose, N-acetyl-D-galactosamine, and N-acetyl-D-glucosamine residues are expressed on the cell surface and in the cytoplasm of Leydig cells during the period from the 13th day p.c. to around the 20th day p.p. The results suggest that these glycoconjugates might play some role in modulating hormone-receptor interaction in the Leydig cells before the 20th day. Furthermore, these results may indicate that sugar residues expressed on the cell surface and in the cytoplasm of Leydig cells are different from those in the fetal-neonatal and adult phases.