Karl J, Capel B
Department of Cell Biology, Duke University Medical Center, Durham, North Carolina, 27710, USA.
Dev Biol. 1998 Nov 15;203(2):323-33. doi: 10.1006/dbio.1998.9068.
During mouse development, the gonad begins to form shortly before 10. 5 days postcoitum (dpc) on the ventromedial side of the mesonephros. The XY gonad consists of germ cells and somatic cells. The origin of the germ cells is clearly established; however, the origin of the somatic cells, especially the epithelial supporting cell lineages, called Sertoli cells, is still unclear. Sertoli cells are the first somatic cell type to differentiate in the testis and are thought to express Sry, the male sex-determining gene, and to play a crucial role in directing testis development. Previous data have suggested that the somatic cells of the gonad may arise from the mesonephric tubules, the mesonephric mesenchyme, or the coelomic epithelium. Immunohistochemical staining of the gonad at 11.5 dpc showed that the basement membrane barrier under the coelomic epithelium is discontinuous, suggesting that cells in the coelomic epithelium at this stage might move inward. To test this possibility directly, cells of the coelomic epithelium were labeled using the fluorescent lipophilic dye, DiI. We show that when labeled at tail somite 15-17 stages, corresponding to 11.2-11.4 dpc, the coelomic epithelial cells of both sexes migrated into the gonad. In XY gonads, the migrating coelomic epithelial cells became Sertoli cells, as well as interstitial cells. This ability of the coelomic epithelium to give rise to Sertoli cells was developmentally regulated. When labeled at tail somite 18-20 stages, corresponding to 11.5-11.7 dpc, the coelomic epithelial cells no longer became Sertoli cells. Instead, cells that migrated into the gonad stayed outside testis cords, in the interstitium. Migration gradually decreased and ceased by tail somite 30 stage, corresponding to 12.5 dpc, after testis cords had formed and the basement membrane layer underlying the coelomic epithelium had thickened to form the tunica albuginea. In XX gonads, coelomic epithelial cells also migrated into the gonad, but there was no obvious fate restriction during the same developmental period. Taken together, our data show that the coelomic epithelium is a source of Sertoli cells as well as other somatic cells of the gonad in the developing mouse testis.
在小鼠发育过程中，性腺在交配后10.5天左右于中肾腹内侧开始形成。XY性腺由生殖细胞和体细胞组成。生殖细胞的起源已明确；然而，体细胞尤其是被称为支持细胞的上皮支持细胞系的起源仍不清楚。支持细胞是睾丸中最早分化的体细胞类型，被认为表达雄性性别决定基因Sry，并在引导睾丸发育中起关键作用。先前的数据表明，性腺的体细胞可能起源于中肾小管、中肾间充质或体腔上皮。对11.5天交配后性腺的免疫组织化学染色显示，体腔上皮下方的基底膜屏障是不连续的，表示此阶段体腔上皮中的细胞可能向内迁移。为了直接测试这种可能性，使用荧光亲脂性染料DiI标记体腔上皮细胞。我们发现，当在尾芽15 - 17期（对应于11.2 - 11.4天交配后）进行标记时，两性的体腔上皮细胞都迁移到了性腺中。在XY性腺中，迁移的体腔上皮细胞变成了支持细胞以及间质细胞。体腔上皮产生支持细胞的这种能力受到发育调控。当在尾芽18 - 20期（对应于11.5 - 11.7天交配后）进行标记时，体腔上皮细胞不再变成支持细胞。相反，迁移到性腺中的细胞停留在睾丸索之外的间质中。到尾芽30期（对应于12.5天交配后），睾丸索形成且体腔上皮下方的基底膜层增厚形成白膜后，迁移逐渐减少并停止。在XX性腺中，体腔上皮细胞也迁移到了性腺中，但在相同的发育时期没有明显的命运限制。综上所述，我们的数据表明，体腔上皮是发育中小鼠睾丸中性腺支持细胞以及其他体细胞的来源。
