1. Induction of Apoptosis during the process of Spermatogenesis 2. DNA breaks during the process of Spermiogenesis. 3. Post testicular DNA fragmentation induces by ROS during sperm transport through the seminiferous tubules and the epididymis. 4. Damage induced by endogenous caspases and endonucleases 5. DNA damage induced by radiotherapy and chemotherapy 6. DNA damage induced by environmental toxicants and life style changes.