Human sperm molecular anatomy: the enzyme 5α-reductase (SRD5A) is present in the sperm and may be involved in the varicocele-related infertility.

The most common cause of male infertility is the testicular varicocele, a condition that impairs production and decreases quality of sperm. Male fertility also strictly depends on androgens acting through their own receptor. The enzyme 5α-reductase (SRD5A) is involved in the conversion of testosterone to 5α-dihydrotestosterone, both required for the development and maintenance of male reproductive function. Here, we evaluated, by western blotting analysis, the presence of SRD5A in human ejaculated spermatozoa and evidenced differences in sperm SRD5A content between healthy donors and varicocele-affected patients. Additionally, SRD5A sperm ultrastructural localization was also assessed by transmission electron microscopy and immunogold assay. We evidenced that SRD5A