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

从供体小鼠中分离雄性生殖细胞，并成功移植到缺乏生殖细胞的小鼠中。以GFP转基因小鼠为供体，在荧光显微镜下观察移植的生殖系干细胞与受体细胞的区别，并追踪其扩增方式。移植后3周，大部分细胞呈未分化的精原细胞样，c-Kit抗体阴性，并形成明显的集落。后来，在殖民地中出现了更多的分化细胞，如分化的精原细胞和精母细胞。通过这种移植系统，我们摄入了促性腺激素拮抗剂亮丙瑞林的作用，亮丙瑞林可抑制垂体分泌促性腺激素，从而提高睾丸内睾酮的产生。当亮丙瑞林被抑制时，供体来源的集落大小增加，显示亮丙瑞林激活精原干细胞的生长。这表明睾酮在精原细胞生长过程中具有抑制作用，这与广泛接受的观点相反，即睾酮是减数分裂阶段后生殖细胞存活和分化所必需的。在寻找亮丙瑞林抑制机制时，我们假设干细胞因子/c-Kit信号系统的可能性最大，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，供体来源的集落在S1/S1受体睾丸中形成，而没有任何有害影响。我们得出结论，亮丙瑞林通过SCF/c-Kit以外的信号传导机制对精原细胞产生影响。

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.