The first round of mouse spermatogenesis is a distinctive program that lacks the self-renewing spermatogonia stage
The first round of mouse spermatogenesis is a distinctive program that lacks the self-renewing spermatogonia stage
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DOI：
10.1242/dev.02316
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发表时间：
2006-04-15
期刊：
影响因子：
4.6
通讯作者：
Nabeshima, Y
中科院分区：
文献类型：
--
作者：
Yoshida, S;Sukeno, M;Nabeshima, Y
哺乳动物的精子发生是由来自自我更新干细胞的分化细胞的持续供应来维持的。干细胞活性存在于原始生殖细胞的一个小的亚群，即未分化的精原细胞。然而，这个群体的建立和分化的启动之间的关系在发展中的睾丸仍然不清楚。在本研究中，我们利用Ngn 3的独特表达来研究这个问题，Ngn 3在未分化的精原细胞中特异性表达，而在分化的精原细胞或其祖细胞--生殖细胞中不表达。我们的谱系分析表明，小鼠精子发生的第一轮直接从生殖细胞开始，而不经过Ngn 3表达阶段（Ngn 3（-）谱系）。相比之下，随后的几轮精子发生源自Ngn 3（-）阳性未分化精原细胞，其也是生殖细胞的直接后代，并代表干细胞功能（Ngn 3（+）谱系）。因此，在小鼠精子发生中，未分化的精原细胞的状态不是一个不可避免的步骤，而是一个确保连续精子产生的发育选择。此外，生殖母细胞分离成未分化的精原细胞（Ngn 3（-）谱系）或分化的精原细胞（Ngn 3（-）谱系）与生精上皮周期的建立在地形学上相关，因此表明体细胞成分在干细胞建立中的作用。
Mammalian spermatogenesis is maintained by a continuous supply of differentiating cells from self-renewing stem cells. The stem cell activity resides in a small subset of primitive germ cells, the undifferentiated spermatogonia. However, the relationship between the establishment of this population and the initiation of differentiation in the developing testes remains unclear. In this study, we have investigated this issue by using the unique expression of Ngn3, which is expressed speci.cally in the undifferentiated spermatogonia, but not in the differentiating spermatogonia or their progenitors, thegonocytes. Our lineage analyses demonstrate that the first round of mouse spermatogenesis initiates directly from gonocytes, without passing through the Ngn3-expressing stage (Ngn3(-) lineage). By contrast, the subsequent rounds of spermatogenesis are derived from Ngn3(-) positive undifferentiated spermatogonia, which are also immediate descendents of the gonocytes and represent the stem cell function (Ngn3(+) lineage). Thus, in mouse spermatogenesis, the state of the undifferentiated spermatogonia is not an inevitable step but is a developmental option that ensures continuous sperm production. In addition, the segregation of gonocytes into undifferentiated spermatogonia (Ngn3(-) lineage) or differentiating spermatogonia (Ngn3(-) lineage) is topographically related to the establishment of the seminiferous epithelial cycle, thus suggesting a role of somatic components in the establishment of stem cells.