Sperm number and condition affect the number of basal cells and their expression of macrophage antigen in the murine epididymis

Unilateral ligation of the mid-corpus epididymis, the proximal vas deferens and imposition of an abdominal temperature for 6 days as well as bilateral castration for 3, 6 or 14 days, resulted in a change in epithelial composition of the adult murine epididymis with regard to the number and antigen expression of basal cells. There were fewer basal cells per tubule cross-section with fewer expressing F4/80 antigen when spermatozoa were absent from the proximal lumen following short-term castration. Conversely, more basal cells with more of them demonstrating macrophage antigen expression were evident when more or damaged spermatozoa were in the proximal lumen after corpus ligation and exposure to abdominal temperature or in the cauda after long-term withdrawal of androgen support. By contrast, ligation of the vas deferens did not lead to tubule distension, and hence sperm accumulation, and did not alter the basal cell population in the cauda epididymis. The data suggest that epididymal basal cells respond in number and macrophage antigen expression to the presence of sperm autoantigens in the lumen with little dependence on circulating androgens. These changes may represent responses to minimise the interaction of sperm autoantigens with the immune system and the risk of immunological infertility.