Male Factors: the Role of Sperm in Preimplantation Embryo Quality.

Few studies have been conducted on the paternal effects on embryogenesis as compared with studies on maternal effects. The fertility potential of sperm decreases with genomic material abnormalities. Damaged DNA of sperm has been correlated with poor fertilization, reduced implantation and pregnancy rates, and increased production of aneuploid embryos. Evidence suggests that the role of sperm in embryogenesis goes beyond genomic material transfer, and centrosomes, sperm-derived cytoplasmic factors, paternal mRNA, and small RNAs are essential for early embryonic development. Epigenetic factors like histone modification and DNA methylation participate in the regulation of gene expression in sperm. The etiology of sperm chromatin abnormalities is important in male fertility and may affect reproductive outcomes. Success in implantation depends on the quality of the fertilized sperm and oocyte as well as the type of assisted reproductive techniques. Therefore, male factors affecting development of embryo can play a role in the failure of assisted reproductive techniques. Further studies are needed to evaluate clinical aspects and the risks of transmitting genetic or epigenetic disorders to provide safe therapies for infertility.