Spermatogenesis, DNA damage and DNA repair mechanisms in male infertility.

Spermatogenesis is a complex process of proliferation and differentiation during male germ cell development involving mitosis, meiosis and spermiogenesis. Endogenous and exogenous physical, chemical and biological sources modify the genome of spermatozoa. The genomic integrity and stability of the sperm is protected by DNA repair mechanisms. In the male germline cells, DNA repair mechanisms include nucleotide excision repair, base excision repair, DNA mismatch repair, double strand break repair and post-replication repair. Defects in repair mechanisms cause arrest of spermatogenesis and abnormal recombination, ultimately resulting in male infertility. This review focuses on molecular mechanisms of the DNA repair pathways, DNA repair defects and male infertility.