Maekawa M, Suzuki-Toyota F, Toyama Y, Kadomatsu K, Hagihara M, Kuno N, Muramatsu T, Dohmae K, Yuasa S
Department of Anatomy and Developmental Biology, Chiba University School of Medicine, Japan.
Arch Histol Cytol. 1998 Dec;61(5):405-15. doi: 10.1679/aohc.61.405.
Ablation of the transmembrane glycoprotein basigin leads to azoospermic mice, indicating that this gene is essential for spermatogenesis. To examine the functions of basigin in the testis, the precise localization of basigin during spermatogenesis was examined immunohistochemically. In the adult mouse testis, basigin immunoreactivity appeared on the cell surface of leptotene spermatocytes and gradually increased in intensity during the meiotic prophase. Cytoplasmic staining, as well as cell surface staining, was detected in spermatids. The most conspicuous reactivity was found in the spermatids at steps 9-11 and in the flagella of spermatids. Immuno-electron microscopic analysis demonstrated that basigin was localized not only on the plasma membranes of spermatocytes and spermatids, but also on the plasma membrane of the Sertoli cell processes which contact the spermatocytes and spermatids. Basigin immunoreactivity was also detected during postnatal development in spermatocytes and spermatids but not in spermatogonia. Experimental cryptorchid testes which contain only spermatogonia and Sertoli cells in the seminiferous epithelium showed no basigin immunoreactivity. Seven days after surgical reversal of the cryptorchid testis, spermatocytes reappeared in the tubules, along with basigin immunoreactivity. Furthermore, in sterile mutant mice, in which neither spermatocytes nor spermatids were generated, no basigin immunoreactivity was detected in the seminiferous tubules. These findings indicate that expression of basigin is concomitant with appearance of spermatocytes in the seminiferous tubule, and suggest that basigin is involved in the interaction between Sertoli cells and germ cells at specific stages of spermatogenesis.
跨膜糖蛋白脑信号素的缺失会导致小鼠无精子症，这表明该基因对精子发生至关重要。为了研究脑信号素在睾丸中的功能，采用免疫组织化学方法检测了精子发生过程中脑信号素的精确定位。在成年小鼠睾丸中，细线期精母细胞的细胞表面出现脑信号素免疫反应性，在减数分裂前期强度逐渐增加。在精子细胞中检测到细胞质染色以及细胞表面染色。在第9 - 11阶段的精子细胞和精子鞭毛中发现了最明显的反应性。免疫电子显微镜分析表明，脑信号素不仅定位于精母细胞和精子细胞的质膜上，也定位于与精母细胞和精子细胞接触的支持细胞突起的质膜上。在出生后发育过程中，精母细胞和精子细胞中也检测到脑信号素免疫反应性，但精原细胞中未检测到。仅在生精上皮中含有精原细胞和支持细胞的实验性隐睾未显示脑信号素免疫反应性。隐睾手术复位7天后，生精小管中重新出现精母细胞，同时伴有脑信号素免疫反应性。此外，在不育突变小鼠中，既不产生精母细胞也不产生精子细胞，在生精小管中未检测到脑信号素免疫反应性。这些发现表明脑信号素的表达与生精小管中精母细胞的出现同步，并提示脑信号素在精子发生的特定阶段参与支持细胞与生殖细胞之间的相互作用。
