Mechanism for the Formation of Seminiferous Tubules in Mammals

用光镜和透射电镜观察了发育中小鼠的生精上皮，以阐明支持细胞的起源。在胎鼠的睾丸从第12天到第14天pc，PAS阳性物质检测到专门在整个细胞质的支持细胞在C57 BL/6小鼠。pc第12天，前支持细胞在生殖细胞周围形成不规则的索状排列，这种排列与体腔上皮无关。这表明支持细胞起源于中肾组织。接下来，我们检测了发育中胎鼠睾丸凝集素结合的变化，以阐明生精小管形成的机制。在三种凝集素中，BS-Ⅰ和BPA在12 - 14天的pc期内优先与生殖细胞的质膜和小致密体结合，这三种凝集素在睾丸发育过程中表现出特征性的结合模式。然而，在胎龄16天的睾丸中，与这两种凝集素的反应完全消失。与GS-Ⅱ的反应仅限于支持细胞从12至14天pc，此后消失的pc第16天。凝集素结合模式的显著变化表明，某些含有D-半乳糖和N-乙酰-D-半乳糖胺残基的糖缀合物在12 ~ 14 dpc期间表达，其功能和结构的变化可能发生在14 ~ 16 dpc期间，与睾丸发育有关。

The seminiferous epithelium in the developing mice was studied by light and transmission electron microscopy to elucidate the origin of Sertoli cells. In the testis of fetal mice from day 12 to day 14 pc, PAS-positive substances were detected exclusively throughout the cytoplasm of Sertoli cells in C57BL/6 mice. On day 12 pc, pre-Sertoli cells formed irregular and cord-like arrangements around germ cells, and the arrangements were not associated with the coelomic epithelium. This suggests that Sertoli cells are originated from the mesonephric tissues. Next, the changes in lectin binding of developing fetal mouse testis were examined to clarify the mechanism of seminiferous tubule formation. out of three lectins, which, showed the characteristic binding pattern during the testicular development, BS-I and BPA preferentially bound to the plasma membrane and small dense bodies of germ cells during 12 to 14 day pc. However, in the fetal testis on day 16 pc, the reaction with these two lectins completely disappeared. The reaction with GS-II was restricted to Sertoli cells from 12 to 14 day pc, and thereafter disappeared on day 16 day pc. The striking changes in lectin binding pattern suggest that certain glyco-conjugates containing D-galactose and N-acetyl-D-galactosamine residues are expressed during the period of 12 to 14 dpc, and the changes in function and structure may take place during 14 to 16 dpc, in association with testicular development.