Reduced sperm yield from testicular biopsies of vasectomized men is due to increased apoptosis

Objective To compare sperm yields, apoptotic indices, and sperm DNA fragmentation from vasectomized men and fertile men undergoing vasectomy. Design Testicular biopsies from vasectomized (n = 26) and fertile men (n = 46), were milked to calculate sperm/gram and also formalin-fixed to determine the numbers of developing sperm and incidence and intensities of testicular FasL, Fas, Bax, and Bcl-2. Testicular sperm DNA fragmentation was assessed using the alkaline Comet assay. Setting An ART unit. Patient(s) Twenty-six men attending for intracytoplasmic sperm injection (ICSI) and 46 men attending for vasectomies. Main Outcome Measure(s) Spermatocyte, spermatid and sperm yields, Fas, FasL, and Bax staining. Result(s) Sperm yields from men vasectomized >5 years previously were markedly reduced compared to fertile men. Increased intensities of FasL and Bax staining were observed in the seminiferous tubules of vasectomy men. FasL positivity (percentage) also increased in Sertoli cells, and both FasL and Fas positivity (percentage) increased in primary spermatocytes and round spermatids of vasectomized men. Sperm DNA fragmentation, an end point marker of apoptosis, increased significantly in vasectomized men compared to fertile men. Conclusion(s) Reduced sperm yields after vasectomy are associated with increased apoptosis through the Fas–FasL and Bax pathways. Sperm after vasectomy displayed increased DNA fragmentation.