[Cytology of the prenatal development of human gonads. I. Histogenesis of the testis, studied on epon sections].
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The authors describe a clinical case of metastatic testicular non-seminomatous germinal tumor with several recurrences treated by the association of chemotherapy and surgery for remaining lesions. Based on this case a review of the literature is done to illustrate the evolution of treatments, to highlight the evolutive potential of mature teratoma, the delayed recurrences.
The enzyme complex 3 beta-hydroxy-5-ene-steroid dehydrogenase/delta 5-delta 4 isomerase (3 beta-HSD) is involved in the biosynthesis of all classes of active steroids, including androgens. To correlate possible changes in 3 beta-HSD with the well-known variations in testosterone secretion during development, the authors localized this enzyme by immunocytochemistry during fetal and postnatal periods of development in the human testis. In the fetal testis, 3 beta-HSD was detected in Leydig cells during the second and third trimester of gestation. In 8-month-old and 11-year-old boys, however, no immunoreaction could be detected in the testis. In pubertal boys, Leydig cells appeared well developed and immunopositive. Since the fluctuations in 3 beta-HSD immunoreactivity are similar to those already observed for androgen secretion, activation of 3 beta-HSD by trophic hormones may play an important role in androgen production during fetal and postnatal development.
Two groups of 6 rams were maintained under constant photoperiodic conditions consisting of short days (8 h light: 16 h dark; Group S) and long days (16 h light; 8 h dark; Group L) from 4 to 20 months of age. Five other rams were reared under a photoperiod representative of that occurring naturally (Group N). Testis size, plasma testosterone and prolactin concentrations were monitored weekly and sexual behaviour tests were carried out at regular intervals. Over the treatment period Groups S and L did not differ in terms of testis growth or plasma testosterone. Both groups had a phase of testis growth and increased testosterone followed by a decline and the temporal patterns for the two groups were equivalent. Sexual behaviour was slower to develop in Group L than in Group S, indicating that photoperiod can affect the development of sexual behaviour irrespective of peripheral plasma testosterone concentrations. Plasma prolactin levels showed a cyclic variation in Group L and were significantly higher overall than in Group S rams. This, together with a trend towards negative correlations between prolactin concentrations and sexual behaviour in Group L, indicates that prolactin may be involved in the effect of photoperiod on sexual behaviour. The presence of a cycle of testicular growth and of hormone concentrations in young animals under constant photoperiod tentatively suggests that these cycles are endogenous. The constant photoperiod did, however, affect the animals because the cycles which occurred in Groups S and L were out of phase with those of Group N by about 4 months.
In the seminiferous epithelium, germ cell development behind the blood-testis barrier involves continual degradation and renewal of inter-testicular cell junctions. This allows: (i) the translocation of developing germ cells from the basal lamina to the adluminal compartment during spermatogenesis, and (ii) the eventual release of mature spermatids into the tubular lumen during spermiation. Throughout spermatogenesis, cellular debris must also be removed from the epithelium Thus, it is conceivable that proteases, protease inhibitors, and cell junctional components are involved in these events. The present study sought to examine whether testicular cells can express multiple cathepsin mRNAs given that these proteases are involved in the degradation and processing of proteins as well as in tissue regeneration. By using total RNA isolated from primary cultures of Sertoli, Leydig, and germ cells for reverse-transcription and polymerase chain reaction (RT-PCR), the mRNAs of cathepsin B, C, D, H, L, and S were shown to be expressed by Sertoli and Leydig cells, whereas germ cells isolated from adult rats expressed all of the above cathepsin mRNAs except cathepsin D. Throughout postnatal development and maturation, the testicular steady-state mRNA levels of cathepsin B, C, D, L, and S remain relatively unchanged with the exception of cathepsin H whose mRNA level increased during maturation and peaked at 45-60 days of age. Using lonidamine, an anti-spermatogenic drug which is known to induce premature release of germ cells without affecting Leydig cell function by disrupting the inter-Sertoli-germ cell junctions, we have examined the differential expression of these cathepsin mRNAs in the testis at the time of extensive tissue restructuring. It was noted that the expression of cathepsin L and S in the testis increased significantly concomitant with the disappearance of elongate spermatids whereas the expression of cathepsin B, C, D, and H increased significantly when most of the round spermatids and spermatocytes were depleted. These results illustrate the intricate inter-relationship between these proteases in the testis during maturation and tissue restructuring.
Gamma-aminobutyric acid and GABAergic receptors were previously reported to be distributed in reproductive systems besides CNS and predicted to participate in the modulation of testicular function. Gamma-aminobutyric acid transporter was implicated to be involved in this process. However, the potential role of gamma-aminobutyric transporter in testis has not been explored. In this study, we investigated the existence of mouse gamma-aminobutyric acid transporter subtype I (mGAT1) in testis. Wild-type and transgenic mice, which overexpressing mGAT1 in a variety of tissues, especially in testis, were primarily studied to approach the profile of mGAT1 in testis. Mice with overexpressed mGAT1 develop normally but with reduced mass and size of testis as compared with wild-type. Testicular morphology of transgenic mice exhibited overt abnormalities including focal damage of the spermatogenic epithelium accompanied by capillaries proliferation and increased diameter of seminiferous tubules lumen. Reduced number of spermatids was also found in some seminiferous tubules. Our results clearly demonstrate the presence of GAT1 in mouse testis and imply that GAT1 is possibly involved in testicular function.
The injection into the dorsal skin of a suspension of guinea pig testis or spermia incorporated in a water-in-oil emulsion containing killed mycobacteria induces aspermatogenesis in guinea pigs. The injury begins with the inhibition of the maturation of spermia and proceeds through the degeneration and exfoliation of spermatids, spermatocytes, and finally spermatogonia. These germinal cells pass from the seminiferous tubules into the epididymis. The process is not associated with inflammation. No significant changes occur in the intertubular spaces and the Leydig cells do not seem to be affected. The seminal vesicles and the prostate remain normal. The aspermatogenesis may begin in 10 days and it lasts for more than 5 months. The process may lead to atrophy of the seminiferous tubules and fibrosis. Guinea pigs which receive a suspension of their own testis or spermia and adjuvants develop a similar injury. The "mitochondrial" fraction of the testis of guinea pig is effective while repeated injections of alcoholic extract of testis emulsified with paraffin oil containing mycobacteria do not cause aspermatogenesis. The presence of acid-fast bacilli in the water-in-oil emulsion containing testis or spermia seems to be essential for the production of testicular lesions; the injection of antigen and mycobacteria into different sites is ineffective. When guinea pig testis is replaced by guinea pig liver or kidney or rabbit testis no testicular damage occurs. The injection of rabbit spinal cord combined with adjuvants results in allergic encephalomyelitis in a large proportion of guinea pigs, accompanied by a great loss of weight. The testes of a few of these animals show a varying degree of aspermatogenesis. When guinea pig brain is combined with adjuvants and administered subcutaneously the incidence of testicular injury is high, although the damage is, in general, mild. From the standpoint of mechanism, the inhibition of spermatogenesis which occurs in these animals may be unrelated to the injury which follows the injection of germinal cells. Aspermatogenesis follows the injection of killed mycobacteria in paraffin oil into the testis as well as into certain sites related to the gonad: the abdominal cavity, the subcutaneous tissue over the abdomen, and the skin of the inguinal region. Antibodies fixing complement in the presence of spermia are demonstrable in the sera of guinea pigs injected with testis or spermia and adjuvants. When the mycobacteria are omitted the titers are low and no testicular injury occurs. Although there seems to be a correlation between testicular damage and complement-fixing titer, this may not be a causal relationship. Antibodies which neutralize guinea pig hyaluronidase and those which immobilize spermia have also been demonstrated in the sera of these guinea pigs.
Aquaporins (AQPs) are membrane protein channels that allow the rapid passage of water through an epithelium containing tight junctions. In the present study, light microscope immunocytochemistry was utilized to localize several members of the AQP family in the testis, efferent ducts, and epididymis of normal adult animals during postnatal development and after various experimental procedures on adult animals. In the testis of normal adult animals, AQP-8 was expressed exclusively in Sertoli cells, while AQP-9 outlined Leydig cells. In the efferent ducts, AQP-1 was expressed on the microvilli, basolateral plasma membranes, and apical endosomes of the nonciliated cells and cilia of ciliated cells, while AQP-9 was present only on the microvilli of nonciliated cells. In the epididymis, AQP-9 was localized to the microvilli of the principal cells of all regions, with the most intense reaction being noted in the initial segment and cauda regions. The clear cells of the cauda region expressed only AQP-9. AQP-1 was not expressed in the testis or the epididymal epithelium, but it was expressed over the endothelial cells of the vascular channels of the efferent ducts and epididymis. After efferent duct ligation or orchidectomy, there was no change in the expression of AQP-1 or -9 over the microvilli or cilia of epithelial cells in the case of the efferent ducts, suggesting that testicular factors do not regulate their expression in this region. In contrast, AQP-9 expression in the principal cells of the initial segment, but not of other regions, and also in the clear cells of the cauda region was dramatically reduced after both treatments. As the expression was not restored to control levels by testosterone replacement, the data suggest that a luminal factor(s) derived from the testis regulates AQP-9 expression in the principal cells of the initial segment and in the clear cells of the cauda region. Postnatal studies revealed that the expression of AQP-1 and -9 in the different cell types of the efferent ducts and epididymis occurred between days 7 and 29, eliminating sperm and high androgen levels as possible regulating factors. Taken together, these data suggest cell specificity with respect to the expression of AQP-8 and -9 in the testis. In the efferent ducts and epididymis, specificity exists in cell, region, and tissue distribution with respect to the expression of AQP-1 and -9, and their expression does not appear to be regulated by androgens.
Mutations in the Wilms' tumor 1 gene, WT1, cause pediatric nephroblastoma and the severe genitourinary disorders of Frasier and Denys-Drash syndromes. High levels of WT1 expression are found in the developing kidney, uterus, and testis--consistent with this finding, the WT1 knockout mouse demonstrates that WT1 is essential for normal genitourinary development. The WT1 gene encodes multiple isoforms of a zinc finger-containing protein by a combination of alternative splicing and alternative translation initiation. The use of an upstream, alternative CUG translation initiation codon specific to mammals results in the production of WT1 protein isoforms with a 68-amino-acid N-terminal extension. To determine the function in vivo of mammal-specific WT1 isoforms containing this extension, gene targeting was employed to introduce a subtle mutation into the WT1 gene. Homozygous mutant mice show a specific absence of the CUG-initiated WT1 isoforms yet develop normally to adulthood and are fertile. Detailed histological analysis revealed normal development of the genitourinary system.
The fetal basis of adult disease is poorly understood on a molecular level and cannot be solely attributed to genetic mutations or a single etiology. Embryonic exposure to environmental compounds has been shown to promote various disease states or lesions in the first generation (F1). The current study used the endocrine disruptor vinclozolin (antiandrogenic compound) in a transient embryonic exposure at the time of gonadal sex determination in rats. Adult animals from the F1 generation and all subsequent generations examined (F1-F4) developed a number of disease states or tissue abnormalities including prostate disease, kidney disease, immune system abnormalities, testis abnormalities, and tumor development (e.g. breast). In addition, a number of blood abnormalities developed including hypercholesterolemia. The incidence or prevalence of these transgenerational disease states was high and consistent across all generations (F1-F4) and, based on data from a previous study, appears to be due in part to epigenetic alterations in the male germ line. The observations demonstrate that an environmental compound, endocrine disruptor, can induce transgenerational disease states or abnormalities, and this suggests a potential epigenetic etiology and molecular basis of adult onset disease.
Contact-mediated interactions between Sertoli cells and gonocytes are important for testicular development. Specifically, down-regulation of neural cell adhesion molecule (NCAM)-based intercellular adhesion during postnatal maturation is likely to be important for appropriate differentiation of testicular cells. Besides NCAM, P-cadherin is also present in neonatal testicular cords, at least in mice, and seems to disappear from the seminiferous epithelium after the first postnatal week. Another factor known to be important in regulating development of the neonatal testis is thyroid hormone (T3). T3 is involved in control of Sertoli cell proliferation and differentiation. Therefore, we examined the effect(s) of T3 on adhesive factors found within the testis using Sertoli cells and gonocytes isolated from neonates and maintained in coculture. T3 (100 nM) down-regulated NCAM expression in vitro, as assessed by Western blotting and immunofluorescent staining. This contrasted with the continued expression of NCAM in cultures without added T3 but mimicked the disappearance of NCAM from the neonatal rat testis in vivo. In addition, Western analysis confirmed that P-cadherin is highly expressed in the developing rat testes, as it is in those of mice. We found that P-cadherin is strongly expressed in gonocytes and weakly expressed in Sertoli cells. Moreover, unlike NCAM, P-cadherin expression diminishes with time in vitro in the absence of added hormones. In parallel with our observations for NCAM, expression of P-cadherin was also apparently decreased by T3 (100 nM). Subsequent quantitative analyses of cultures exposed to a range of T3 levels (0.1-100 nM) indicated that T3 causes detachment of many gonocytes in a dose- and time-dependent manner (approximately 80% detached at 100 nM). In addition, Western blotting indicated that lower concentrations of T3 down-regulate NCAM but not P-cadherin. From this we conclude that the apparent decrease in P-cadherin induced by 100 nM T3 and detected on Western blots reflects loss of gonocytes. In contrast, even low levels of T3 appear to down-regulate NCAM production before any significant detachment of gonocytes. Finally, low levels of T3 that did not affect numbers of adherent Sertoli cells nevertheless caused detachment of gonocytes. Thus, our observations identify T3 as a regulator of NCAM expression in neonatal testicular cells and as a modifier of gonocyte/Sertoli cell adhesion in vitro.
The transcription factor GATA-4 is expressed in Sertoli cells, steroidogenic Leydig cells, and other testicular somatic cells. Previous studies have established that interaction between GATA-4 and its cofactor FOG-2 is necessary for proper Sry expression and all subsequent steps in testicular organogenesis, including testis cord formation and differentiation of both Sertoli and fetal Leydig cells. Since fetal Leydig cell differentiation depends on Sertoli cell-derived factors, it has remained unclear whether GATA-4 has a cell autonomous role in Leydig cell development. We used two experimental systems to explore the role of GATA-4 in the ontogeny of testicular steroidogenic cells. First, chimeric mice were generated by injection of Gata4-/- ES cells into Rosa26 blastocysts. Analysis of the resultant chimeras showed that in developing testis Gata4-/- cells can contribute to fetal germ cells and interstitial fibroblasts but not fetal Leydig cells. Second, wild-type or Gata4-/- ES cells were injected into the flanks of intact or gonadectomized nude mice and the resultant teratomas examined for expression of steroidogenic markers. Wild-type but not Gata4-/- ES cells were capable of differentiating into gonadal-type steroidogenic lineages in teratomas grown in gonadectomized mice. In chimeric teratomas derived from mixtures of GFP-tagged Gata4+/+ ES cells and unlabeled Gata4-/- ES cells, sex steroidogenic cell differentiation was restricted to GFP-expressing cells. Collectively these data suggest that GATA-4 plays an integral role in the development of testicular steroidogenic cells.
Summary Insulin-like growth factor-I (IGF-I) is involved in the regulation of growth and differentiation of a variety of vertebrate tissues. The biological actions of IGF-I are mediated mainly by the IGF-I receptor (IGF-IR) and partly by the insulin receptor (IR) and modulated by IGF binding proteins (IGFBP). We conducted studies designed to clarify the possible roles of IGF system in the development of the avian reproductive organs. We cloned cDNAs of IGF-I, IGF-IR, IR and IGFBP-2 of Japanese quail and simultaneously measured the expression of these genes in the quail liver, testis and oviduct at different ages using a lysate RNase protection assay. Hepatic IGF-I mRNA levels increased rapidly and remained elevated during the rapid-growing period, which coincided with the period of rapid increase in testicular weight. IGF-I mRNA was detected at each stage of developing testis examined. Its level was high at the early stage and decreased with age. IGFBP-2 mRNA in testis exhibited a similar expression pattern to that of IGF-I, whereas a divergence in IGF-I and IGF-IR gene expression was observed. Both IGF-IR and IR mRNAs increased when the testis grew rapidly and decreased when sexual maturation was almost completed. These results suggest that IGF-I may serve as an autocrine/paracrine regulator as well as an endocrine regulator in the testicular development and function of Japanese quail. In the oviduct, IGF-I, IGF-IR, IR and IGFBP-2 mRNAs were also developmentally regulated. A rapid growth of the oviduct was accompanied by a significant increase in the level of IGF-I mRNA. The expression of genes encoding IGF-IR, IR and IGFBP-2 in the oviduct exhibited a similar developmental change to that of IGF-I. These results suggest that IGF-I mainly works in an autocrine and/or paracrine manner in the oviduct during the development of this organ. The findings of the present study provide further evidence of an important role for IGF system in the development and function of the avian reproductive system.
Sox3 is expressed in developing gonads and in the brain. Evolutionary evidence suggests that the X-chromosomal Sox3 gene may be the ancestral precursor of Sry, a sex-determining gene, and Sox3 has been proposed to play a role in sex determination. However, patients with mutations in SOX3 exhibit normal gonadal determination but are mentally retarded and have short stature secondary to growth hormone (GH) deficiency. We used Cre-LoxP targeted mutagenesis to delete Sox3 from mice. Null mice of both sexes had no overt behavioral deficits and exhibited normal GH gene expression. Low body weight was observed for some mice; overgrowth and misalignment of the front teeth was observed consistently. Female Sox3 null mice (-/-) developed ovaries but had excess follicular atresia, ovulation of defective oocytes, and severely reduced fertility. Pituitary (luteinizing hormone and follicle-stimulating hormone) and uterine functions were normal in females. Hemizygous male null mice (-/Y) developed testes but were hypogonadal. Testis weight was reduced by 42%, and there was extensive Sertoli cell vacuolization, loss of germ cells, reduced sperm counts, and disruption of the seminiferous tubules. We conclude that Sox3 is not required for gonadal determination but is important for normal oocyte development and male testis differentiation and gametogenesis.
The epididymis of the cock is divided into a main part and an appendix epididymidis. The main part of the epididymis is firmly connected to the testis. The sperm transporting tubes open into the ductus epididymidis along its entire length. The rete testis, as the most proximal part of the epididymis, develops from mesenchym cells. The rete testis connects the tubuli seminiferi with the ductuli efferentes proximales which develop from the Bowman's capsules of the mesonephros. The ductuli efferentes distales develop from the proximal tubules, conducting segments (loops of Henle), and the distal tubules of the mesonephros. The short ductuli conjugentes which open into the ductus epididymidis, originate from the connecting segments of the mesonephros. In the sexually mature cock the rete testis, the ductuli efferentes proximales, and the ductus epididymidis all show an enlargement in the lumen. In the ductuli efferentes proximales and in the ductus epididymidis one can observe a formation of globuli and cell protrusion which lead to a loss of the surface structure of the epithelial cells. The appendix epididymidis and the capsula fibrosa of the adrenal gland are joined by connective tissue. The appendix epididymidis consists of the blindly ending ductus aberrans (the crainal continuation of the ductus epididymidis) and the ductuli aberrantes which open into the ductus aberrans. The blind ends of the ductuli aberrantes end in the capsula fibrosa of the adrenal gland.
Cyclophosphamide is a widely used anticancer and immunosuppressive drug that affects fertility in men. In a previous study, we found that chronic, daily treatment of male rats with low doses of cyclophosphamide had no apparent effect on the pituitary-gonadal axis, whereas it had time- and dose-dependent effects on male reproductive organ weights, the hematologic system, and on pregnancy outcome. To determine whether cyclophosphamide induces morphological changes within the male reproductive system, a detailed qualitative and quantitative evaluation of changes in the histology of the testis and epididymis was undertaken. Adult male Sprague-Dawley rats were gavage-fed for 1, 3, 6, and 9 wk with saline (control), 5.1 (low dose) or 6.8 (high dose) mg/kg/day of cyclophosphamide; the testes and epididymides were prepared for light and electron microscopy. At the light microscopic level, the orderly process of spermatogenesis in the seminiferous tubules was not affected at any time point with either dose of the drug. A number of time-dependent drug-induced changes in the histology of the epididymis, however, were apparent: 1) an increase in the relative number and a change in the distribution of halo cells in the caput epididymidis, 2) an increase in the number and size of clear cells in the caput and/or cauda epididymidis, and 3) an increase in the size of clear cells in both the caput and cauda epididymides; these changes were time dependent. At the electron microscopic level, there was a dose-dependent, two- to threefold increase in the number of spermatozoa with abnormal flagellar midpieces in the lumen of both the caput and cauda epididymides. Although the 9 plus 2 axonemal complex and the 9 outer dense fibers were present and appeared normal, the close approximation of these two structures was lost in these abnormal spermatozoa. Such abnormal flagellar midpieces were also found in the testes of control and treated rats. Electron microscopic examination of the testis revealed that both Sertoli and Leydig cells were normal in appearance. The type and timing of the effects of cyclophosphamide on the histology of the testis and epididymis suggest that the drug could be affecting germ cells by 1) inducing changes in the developing spermatozoa in the testis, some of which are seen microscopically in the epididymal lumen, and/or 2) affecting epididymal morphology and function.
A 52-year-old man developed malignant peritoneal mesothelioma 17 years after radiotherapy for seminoma of the testis. Although asbestos exposure is considered to be the major risk factor for the development of malignant mesothelioma, prior therapeutic radiation has also been postulated as a causative factor. The unexplained appearance of ascites or pleural effusion within a previously irradiated area should be considered suggestive of malignant mesothelioma in any long-term survivor of cancer. In addition, the patient suffered a deep vein thrombosis four years before the diagnosis of mesothelioma. Deep vein thrombosis is a common complication of malignant disease, and is often the first clue to occult malignancy.
Sex determination in mammals is mediated via the supporting cell lineage in the fetal gonad. In the very early stages of gonadal development, the fate of the supporting cell population is critically dependent on the expression of the male-determining gene on the Y chromosome. If this gene is absent or fails to be expressed, or is expressed too late or in too small a number of supporting cells, all supporting cells (XX or XY) differentiate as pre-follicle cells and development proceeds along the female pathway. Supporting cells in which the male-determining gene is expressed in a timely manner differentiate as pre-Sertoli cells; given sufficient such cells, testis cords form and development proceeds in a male direction. If XX supporting cells are also present, a few may be recruited into the pre-Sertoli population and participate in testis cord formation. The subsequent fate of pre-follicle cells depends critically on interaction with the germ cell population in the developing gonad: absence of germ cells may lead to partial masculinization of the gonad, and/or to disappearance of the supporting cell component.