Cul4A is essential for spermatogenesis and male fertility

► Cul4A−/− male mice are infertile due to severe deficiencies in spermatogenesis. ► Loss of CUL4A disrupts meiosis at the end of prophase I and increases cell death. ► Cul4A−/− pachytene spermatocytes exhibit persistent DSBs signifying deficient HR. ► CUL4A localizes to the sites of DSBs, suggesting a direct role in HR.