Kanatsu-Shinohara Mito, Morimoto Takeshi, Toyokuni Shinya, Shinohara Takashi
Horizontal Medical Research Organization, Graduate School of Medicine, Kyoto University, Japan.
Biol Reprod. 2004 Jun;70(6):1731-7. doi: 10.1095/biolreprod.103.025668. Epub 2004 Feb 6.
Spermatogenesis originates in spermatogonial stem cells, which have the unique mode of replication. It is considered that a single stem cell can produce two stem cells (self-renewing division), one stem and one differentiating (asymmetric division), or two differentiating cells (differentiating division). However, little is known regarding how each type of division is regulated. In this investigation, we focused on the analysis of self- renewing division and examined the effect of the pituitary gland using two models of stem cell self-renewing division. In the first experiment using newborn mice, the administration of GnRH- analogue, which represses the release of gonadotropin, reduced the number of stem cells during postnatal testicular development, suggesting that the pituitary gland enhances stem cell self- renewing division. In the second experiment, however, the number of stem cells increased dramatically in hypophysectomized adult recipients after spermatogonial transplantation. Thus, the pituitary gland affects the self-renewing division of stem cells, but these contradictory results suggest that its role may be different depending on the stage of the testicular development.
精子发生始于精原干细胞，精原干细胞具有独特的复制模式。一般认为，单个干细胞可产生两个干细胞（自我更新分裂）、一个干细胞和一个分化细胞（不对称分裂）或两个分化细胞（分化分裂）。然而，对于每种分裂类型是如何调控的，人们了解甚少。在本研究中，我们着重分析自我更新分裂，并使用两种干细胞自我更新分裂模型研究垂体的作用。在第一项使用新生小鼠的实验中，给予抑制促性腺激素释放的促性腺激素释放激素（GnRH）类似物，会减少出生后睾丸发育过程中的干细胞数量，这表明垂体可增强干细胞的自我更新分裂。然而，在第二项实验中，精原细胞移植后，垂体切除的成年受体中的干细胞数量急剧增加。因此，垂体影响干细胞的自我更新分裂，但这些相互矛盾的结果表明，其作用可能因睾丸发育阶段的不同而有所差异。
