Different expression of B7-H3 in the caput, corpus, and cauda of the epididymis in mouse

BACKGROUND: B7-H3, a member of the B7 family of the Ig superfamily of proteins, has been detected in the epididymis, which is a storage organ related to sperm maturation. However, the characteristics of its expression in different regions of the epididymis remain unknown. Our aim was to investigate the expression of B7-H3 in the caput, corpus, and cauda of the epididymis. METHODS: We extracted epididymis specimens from adult male C57BL/6 mice. The expression of B7-H3 was then measured with immunohistochemistry, enzyme-linked immunosorbent assay (ELISA) and western blotting. RESULTS: B7-H3 protein was predominantly detected on the membrane and in the cytoplasm of the principal cells in the epididymis. Moreover, the level of B7-H3 in the corpus of the mouse epididymis was significantly higher than that in the caput (p < 0.05) or the cauda of the epididymis (P < 0.05). However, there was no remarkable difference in the level of B7-H3 between the caput and the cauda (p > 0.05). CONCLUSIONS: The caput, corpus, and cauda of the mouse epididymis all expressed B7-H3 protein. However, the levels of B7-H3 were different in the three regions of the epididymis.