Boitani C, Stefanini M, Fragale A, Morena A R
Institute of Histology and General Embryology, University of Rome La Sapienza, Italy.
Endocrinology. 1995 Dec;136(12):5438-44. doi: 10.1210/endo.136.12.7588293.
The action of activin-A on Sertoli and spermatogonial cell proliferation during early postnatal life was studied by using in vitro organ culture of testis fragments from 9-day-old rats. Activin significantly stimulated 3H-thymidine incorporation into testis fragments cultured for 3 days in the presence of FSH, whereas it had no effect in the absence of the hormone. This effect was dose dependent in the range 10-200 ng/ml and was specifically inhibited by the activin-binding protein, follistatin. The effect of activin upon proliferation of different testicular cells was studied in detail by 5-bromo-2'-deoxyuridine-labeling fragments at the end of in vitro culture and then determining percentages of different labeled cells on immunostained histological sections. Concomitant treatment with FSH and activin, but not with FSH or activin alone, significantly stimulated Sertoli cell proliferation but markedly depressed that of differentiating type A spermatogonia. In contrast, proliferative activity of undifferentiated type A spermatogonia was independent of activin, irrespective of the presence of FSH. The effect of donor animal age was then investigated by culturing fragments derived from 3- and 18-day-old rats for 3 days. An age-related response was evident. Sertoli cell proliferation was stimulated by FSH alone in fragments from 3-day-old rats, activin having no apparent effect at this age. In contrast, none of the hormones tested either alone or in combination was effective in 18-day-old animals. These results demonstrate that activin acts with FSH in maintaining mitotic potentiality of Sertoli cells in a defined phase of their maturation path, when their proliferative activity is approaching the final arrest. These findings suggest that activin may be an important local factor in regulating Sertoli cell number and that the mitosis of differentiating spermatogonia subsides during Sertoli cell proliferation.
利用9日龄大鼠睾丸片段的体外器官培养，研究了出生后早期激活素 - A对支持细胞和精原细胞增殖的作用。在促卵泡激素（FSH）存在的情况下，激活素显著刺激了培养3天的睾丸片段中3H - 胸腺嘧啶核苷的掺入，而在无该激素时则无作用。这种作用在10 - 200 ng/ml范围内呈剂量依赖性，并被激活素结合蛋白卵泡抑素特异性抑制。通过在体外培养结束时用5 - 溴 - 2'-脱氧尿苷标记片段，然后在免疫染色组织切片上确定不同标记细胞的百分比，详细研究了激活素对不同睾丸细胞增殖的影响。FSH和激活素联合处理，而非单独使用FSH或激活素，显著刺激了支持细胞增殖，但明显抑制了分化型A精原细胞的增殖。相比之下，未分化型A精原细胞的增殖活性与激活素无关，无论FSH是否存在。然后通过培养来自3日龄和18日龄大鼠的片段3天来研究供体动物年龄的影响。明显存在与年龄相关的反应。在3日龄大鼠的片段中，单独的FSH刺激了支持细胞增殖，此时激活素无明显作用。相反，在18日龄动物中，单独或联合测试的激素均无效。这些结果表明，在支持细胞成熟路径的特定阶段，当它们的增殖活性接近最终停滞时，激活素与FSH共同作用维持支持细胞的有丝分裂潜能。这些发现表明激活素可能是调节支持细胞数量的重要局部因素，并且在支持细胞增殖期间，分化型精原细胞的有丝分裂减弱。
