A research on the character and the specific gene expression of spermatogonial stem cells

从供体小鼠中分离出雄性生殖细胞，并成功地将其移植到没有生殖细胞的小鼠体内。以GFP转基因小鼠为供体，可将移植的生殖系干细胞与受体细胞区分开来，并在荧光显微镜下追踪其扩增方式。移植后3周，大部分移植细胞为未分化的精原细胞，对c-Kit抗体呈阳性反应，并形成明显的集落。在这个移植系统中，我们研究了促性腺激素拮抗剂亮丙瑞林的作用，它抑制了垂体促性腺激素的分泌，从而增加了睾丸内睾酮的产生。当给予亮丙瑞林时，供者来源的集落增大，表明亮丙瑞林激活了精原干细胞的生长。这表明了睾酮在精原细胞生长过程中的抑制作用，这与普遍接受的睾酮是生殖细胞在减数分裂后的生存和分化所必需的观点相反。为了寻找亮丙瑞林抑制的机制，我们假设干细胞因子/c-Kit信号系统的可能性最高，并研究了亮丙瑞林在不表达干细胞因子的S1/S1突变小鼠中的作用。然而，供体来源的克隆是在S1/S1受体睾丸中形成的，没有任何不良影响。我们得出结论，亮丙瑞林通过SCF/c-Kit以外的信号机制对精原细胞发挥作用。

Male germ cells were isolated from donor mice, and successfully transplanted in mice devoid of germ cells. By using GFP transgenic mice as donors, transplanted germline stem cells could be distinguished from the cells of recipients, and their mode of expansion were traced under a fluorscent microscope. Three weeks after transplantation, most of the transplanted cells were undifferentiated spermatogoniae megative to c-Kit antibody, and formed distinct colonies. Later, more differentiated cells such as differentiated spermatogoniae and spermatocytes appeared in the colony.With this transplantation system, we ingestigated the effect of a gonadotropin antagonist, leuprorelin, which suppresses the secretion of gonadotropin from the pituitary and thus raise the intratesticular production of testosterone.When leuprorelin was adiministered, donor-derived colonies increased in size, showing the activation of growth of spermatogonial stem cells by leuprorelin. This indicates the inhibitory effect of testosterone in the process of spermatogonial growth, which is in contrast to the widely-accepted notion that testosterone is necessary for the survival and differentiation of germ cells after the meiotic stage.In search for the mechanism of leuprorelin inhibition, we hypothesized that stem cell factor/c-Kit signalling system has the highest possibility, and investigated the effect of leuprorelin in Sl/Sl mutant mice which do not express stem cell factor. The donor derived colonies, however, were formed in the Sl/Sl recipeint testes without any detrimental effect. We concluded that leuprorelin showed its effect on spermatogoniae through signalling mechanisms other than SCF/c-Kit.