Toyama Y, Maekawa M, Kadomatsu K, Miyauchi T, Muramatsu T, Yuasa S
Department of Anatomy and Developmental Biology, School of Medicine, Chiba University, Japan.
Anat Histol Embryol. 1999 Jul;28(3):205-13. doi: 10.1046/j.1439-0264.1999.00194.x.
Basigin is a transmembrane protein belonging to the immunoglobulin superfamily. In the light of the fact that knockout mice lacking the basigin gene (Bsg) are azoospermic, the phenotype in the male reproductive system was extensively examined in this study. Spermatogenesis in Bsg (-/-) mice was found to be disrupted, and arrested at the metaphase of the first meiotic division. A few germ cells differentiated into young spermatids, but they were exfoliated. The lumens of the male reproductive system were filled with round degenerated cells. Using the TUNEL method and electron microscopy, some of the degenerated cells in the testis and epididymal head were shown to be apoptotic. Crystalloids of fine tubules and unusual ectoplasmic specializations were also observed in the Sertoli cells of Bsg (-/-) mice. These specializations displayed unusual 'circular' structures. Furthermore, unusual ectoplasmic specializations covering the spermatocytes rather than the mature spermatids were found. These structures were formed as a result of the lack of mature spermatids in the Bsg (-/-) testis. Results from analyses of azoospermia in the Bsg (-/-) mice suggest that basigin, through the interactions between germ cells and Sertoli cells, is an essential factor in the growth and/or survival of spermatids.
基底膜蛋白是一种属于免疫球蛋白超家族的跨膜蛋白。鉴于缺乏基底膜蛋白基因（Bsg）的基因敲除小鼠无精子症，本研究对雄性生殖系统中的表型进行了广泛研究。发现Bsg（-/-）小鼠的精子发生受到破坏，并停滞在第一次减数分裂的中期。少数生殖细胞分化为年轻的精子细胞，但它们会脱落。雄性生殖系统的管腔充满了圆形的退化细胞。使用TUNEL法和电子显微镜观察，发现睾丸和附睾头部的一些退化细胞是凋亡细胞。在Bsg（-/-）小鼠的支持细胞中还观察到细管晶体和异常的外质特化。这些特化显示出异常的“圆形”结构。此外，还发现覆盖精母细胞而非成熟精子细胞的异常外质特化。这些结构是由于Bsg（-/-）睾丸中缺乏成熟精子细胞而形成的。对Bsg（-/-）小鼠无精子症的分析结果表明，基底膜蛋白通过生殖细胞与支持细胞之间的相互作用，是精子细胞生长和/或存活的重要因素。
