[Testosterone-induced spermatogenic impairment is associated with looser arrangement of spermatogenic cells in rats].

OBJECTIVE: To determine whether testosterone-induced intra-testicular testosterone withdrawal and therefore spermatogenic impairment is associated with looser arrangement of spermatogenic cells in rats. METHODS: Adult male SD rats received intramuscular injection of testosterone undecanoate at 19 mg/(kg x 15 d) for 130 days, and then testicular tissue blocks were obtained for the preparation of methacrylate resin-embedded sections and observation of the changes in testicular histology. RESULTS: Apart from such changes as impaired spermiogenesis and spermiation, apparently looser arrangement of spermatogenic cells was seen in 11.5% of the seminiferous tubule profiles, with radial cracks (empty spaces) running towards the tubule lumen being formed between lines, bundles or groups of spermatogenic cells (mainly spermatids and spermatocytes). CONCLUSION: Looser arrangement of spermatogenic cells is one of the key histological changes resulting from intra-testicular testosterone withdrawal in rats.

Histological changes of the testis and epididymis in adult rats as a result of Leydig cell destruction after ethane dimethane sulfonate treatment: a morphometric study.

AIM: To quantitatively study the histological changes of the testis and epididymis as a result of a drastic reduction of testosterone secretion. METHODS: Fourteen adult Sprague-Dawley rats were injected intraperitoneally with ethane dimethane sulfonate (EDS, 75 mg/kg) and the same number of animals were injected with normal saline as a control. At days 7 and 12 (after treatment), respectively, half of the animals from each group were killed. The testes and epididymides were removed and tissue blocks embedded in methacrylate resin. The cell number per testis was estimated using the stereological optical disector and some other parameters were obtained using other morphometric methods. RESULTS: The EDS treatment resulted in an almost complete elimination of Leydig cells but had no effect on the numbers of Sertoli cells per testis. At day 7 after EDS treatment, many elongated spermatids were retained in the seminiferous epithelium and many round spermatids could be seen in the epididymal ducts. At day 12, a looser arrangement of spermatids and spermatocytes became evident, with apparent narrow empty spaces being formed between germ cells in an approximately radial direction towards the tubule lumen; the numbers (per testis) of non-type B spermatogonia and spermatocytes were similar to controls, whereas that of type B spermatogonia increased by 59%, and that of early round, elongating and late elongated spermatids decreased by 37%, 72% and 52%, respectively. CONCLUSION: The primary spermatogenic lesions following EDS administration were (i) spermiation failure and (ii) detachment of spermatids and spermatocytes associated with impairment in spermiogenesis and meiosis.

Quantitative (stereological) study of the effects of vasectomy on spermatogenesis in rabbits.

Using stereological methods, especially the optical disector for unbiased estimation of nuclear number, our recent study demonstrated that long-term (6 or 12 months) vasectomy in the rhesus monkey had no significant effects on spermatogenesis (Peng et al. Reproduction 2002, 124, 847-856). This study aimed to determine the scenario in the rabbit using the same morphometric methodology. Three groups of normal male Japanese white rabbits (aged 4-5 months) were subjected to unilateral vasectomy; 10 days, 6 months and 12 months later both testes and epididymides were removed. Testicular and epididymal methacrylate-embedded sections were obtained for stereology. Vasectomy-induced damage to spermatogenesis was observed, primarily sloughing of spermatogenic cells with a greater reduction in the number of advanced (adluminal) cells. The damage was most severe at 10 days, occurring in all the testes on the vasectomized side and involving sloughing of even type A spermatogonia, the number of which returned to normal at 6 and 12 months. Damage was less severe at 6 and 12 months, being found in half of the testes of the vasectomy side, in which the total numbers of later germ cell types were 24.0-59.1% (spermatocytes) and 0.3-11.6% (spermatids) of control at 6 months, and 20.1-22.1% (spermatocytes) and 0.4-12.0% (spermatids) of control at 12 months. By contrast, Sertoli cell number per testis was unchanged following vasectomy in any group. Epididymis on the vasectomy side, especially at 10 days and 6 months, appeared larger than on the contralateral side, but this difference was not statistically significant, and no sperm granuloma was seen in the epididymis.