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Subcellular localization of gonadotropins and testosterone in the developing fetal rat testis.

Gonadotropins and testosterone were immunocytochemically localized in the fetal rat testes 16-18 days of gestation with the unlabeled antibody-peroxidase anti-peroxidase complex technique. Maximum staining for gonadotropins with antiserum to the beta chain of human chorionic gonadotropin (anti-hCGbeta) occurred at 16 days gestation in the seminferous tubule and 17 days gestation in interstitial (Leydig) cells. Anti hCGbeta sites were on the plasma membranes at the luminal aspects of Sertoli cells at 16 days gestation. In addition, intracellular hCGbeta sites were evident including the nucleus, nucleolus, ribosomes, some vesicles, lysosomes and centrioles. The stain for hCGbeta disappeared rapidly and by 17 days was limited to patches in the cytoplasm and nuclei. In the fetal testes, staining for anti-testosterone binding sites was most intense at 18 days of gestation either in lipid droplets or on nuclei of Leydig and Sertoli cells. Very little testosterone stain was observed before 18 days of gestation. These findings agree with physiologic data that suggest that gonadotropins bind to receptors and stimulate testicular development and the capacity for testosterone production.

Animals↗

Variations in soluble and particulate ABP of rat testis during sexual development.

Androgen binding activity (ABP) was determined in two different fractions of developing rat testicular homogenates: in cytosol (cABP) and in a particulate fraction isolated by differential centrifugation (pABP). Homogenates were prepared under stabilization conditions by adding 350 nM testosterone to the homogenization buffer. cABP and pABP concentrations were maximal in 22- to 32-day-old animals, to decrease thereafter during sexual maturation. However, both cABP and pABP increased with age when results were expressed on a per organ basis. pABP could be solubilized under conditions in which it could retain its binding activity. It was then photoaffinity labeled and chromatographed on a Sephadex G 200 column using cytosolic epididymal ABP as a control. Similarities between cABP and pABP include not only the same androgen binding characteristics but also the same exclusion volume after Sephadex G 200 chromatography. Since pABP is only present in Sertoli cells, it might represent ABP before being secreted. Because of its intracellular localization, it could play a role in the compartmentalization of androgens within the testis.

Androgen-Binding Protein↗

Developmental expression of p63 in the mouse testis.

p63 is a member of the p53 gene family and have structural similarities with p53. p63 encodes for multiple isotypes either with N-terminal transactivation domain (TAp63) or without it (DeltaNp63). In the mammalian testis, it has been shown that p53 plays important roles in the regulation of germ cell apoptosis and meiosis. However, little is known for the physiological function of p63 in the mammalian spermatogenesis. To investigate the potential roles of p63 in the developing mouse testis, we examined the expression pattern of p63 in the mouse testis from birth to adulthood. In addition to the TAp63 mRNA which was continuously expressed in the developing testis, transcripts encoding DeltaNp63 was detected at specific stages of testicular development by RT-PCR, from postnatal day 1 to day 7 and from 3 weeks to 4 weeks after birth. Western blot analysis of whole testis lysates with anti-p63 antibody revealed an approximately 68 kD band throughout development and a less abundant protein at 60 kD in the earlier period of postnatal development. Immunopositive reactions for p63 were observed as early as 10 days after birth and p63 protein was localized to the nuclei of spermatocytes and round spermatids. These findings strongly suggest that p63 might be involved in the regulation of proliferation and differentiation of spermatogenic cells in the developing mouse testis.

Animals↗

[Development of the rete testis in the prenatal ontogeny of rodents and effect of prolactin and thyrotropin on its cellular differentiation].

The development of rete testis in the rat, rabbit and guinea pig foetuses has been studied, as well as the influence of prolactin and thyrotropin on differentiation of its cells. It was shown that the rete testis tubules, as well as the seminiferous tubules develop from sex cords, which were derived from coelomic epithelium cells and gonocytes. The development of seminiferous tubules and rete testis was described at various stages of prenatal ontogenesis. Thyrotropin and prolactin exert different effects on differentiation of the rete testis cells: the former increases the mitotic activity of gonocytes and the latter increases that of epithelial cells and enhances degenerative processes in primary germ cells.

Animals↗

A quantitative study of seminiferous tubular cells in the developing Murrah buffalo testis.

We report here a systematic quantitative study of the seminiferous tubular cells of Murrah buffaloes. The most advanced germ cell types in the different age groups (months) were A(0) spermatogonia (SG) (1 and 3), early pachytene (6 and 9), late pachytene (12), secondary spermatocytes (15 and 18), elongating spermatids (21 and 24), elongated spermatids attached to Sertoli cells (30), elongated spermatids detached from Sertoli cells (36) and spermatozoa (42 and 48). Central primitive Sertoli cells (CPSC) and basal primitive Sertoli cells (BPSC) were present in the sex cord of one-month-old calves, while Sertoli cells (SC) were first seen in nine-month-old calves. The number of gonocytes were maximal at six months but they were not seen after this time. Prespermatogonia (PSG) and SG were at a maximum at nine months of age but PSG were not seen after 36 months. The number of SG decreased significantly after nine months up to 36 months of age. Although spermatocytes and spermatids appeared in earlier developmental stages, a rapid increase in their number was recorded after 36 months. The number of SC was maximal in 18-month-old animals. BPSC predominated in the sex cord of animals aged one to six months, SG at 9-12 months of age, primary spermatocytes from 15-30 months and spermatids from 36 to 72 months and in older animals. We concluded that a decrease in the number of SG in buffalo calves after nine months of age might be responsible for a delay in sexual maturity. Moreover, the small number of spermatocytes and spermatids present before 36 months of age may be associated with the low yield of different germ cell divisions and with the cellular degeneration. A rapid increase in the number of spermatocytes and spermatids after 36 months resulted in sexual maturity between 42 and 48 months.

Age Factors↗

Changes in interstitial cells during development of buffalo testis.

Interstitial cells were identified and counted in the testis of Murrah buffalo calves and bulls at the age of 1, 3, 6, 9, 12, 15, 18, 21, 24, 30, 36, 42, 48 and 72 months and older. Six types of cells were identified in the testicular interstitium of 1-month-old calves. These were mesenchymal cells, fetal type Leydig cells, fibroblasts, myoid cells, pericytes and endothelial cells. Adult Leydig cells were visible in 3-month-old calves, but mesenchymal cells were not seen from 18 months onwards. The percentage of mesenchymal cells reached a maximum in 1 month, fetal type Leydig cells in 3 months, adult Leydig cells in 72 months and beyond, fibroblasts in 36 months, myoid cells in 18 months, pericytes in 21 months and endothelial cells after 15 months. Changing percentages of various interstitial cells revealed that myoid cells may have differentiated into fibroblasts and mesenchymal cells, which then differentiated into adult Leydig cells.

Animals↗

Cell proliferation and hormonal changes during postnatal development of the testis in the pig.

Histometrical evaluation of the testis was performed in 36 Piau pigs from birth to 16 mo of age to investigate Sertoli cell, Leydig cell, and germ cell proliferation. In addition, blood samples were taken in seven animals from 1 wk of age to adulthood to measure plasma levels of FSH and testosterone. Sertoli cell proliferation in pigs shows two distinct phases. The first occurs between birth and 1 mo of age, when the number of Sertoli cells per testis increases approximately sixfold. The second occurs between 3 and 4 mo of age, or just before puberty, which occurs between 4 to 5 mo of age, when Sertoli cells almost double their numbers per testis. The periods of Sertoli cell proliferation were concomitant with high FSH plasma levels and prominent elongation in the length of seminiferous cord/tubule per testis. Leydig cell volume increased markedly from birth to 1 mo of age and just before puberty. In general, during the first 5 mo after birth, Leydig cell volume growth showed a similar pattern as that observed for testosterone plasma levels. Also, the proliferation of Leydig cells per testis before puberty showed a pattern similar to that observed for Sertoli cells. However, Leydig cell number per testis increased up to 16 mo of age. Substantial changes in Leydig cell size were also observed after the pubertal period. From birth to 4 mo of age, germ cells proliferated continuously, increasing their number approximately two- to fourfold at each monthly interval. A dramatic increase in germ cells per cross-section of seminiferous tubule was observed from 4 to 5 mo of age; their number per tubule cross-section stabilized after 8 mo. To our knowledge, this is the first longitudinal study reporting the pattern of Sertoli cell, germ cell, and Leydig cell proliferative activity in pigs from birth to adulthood and the first study to correlate these events with plasma levels of FSH and testosterone.

Animals↗