Environmental and external stressors of postejaculatory sperm function.

Mature mammalian spermatozoa are one of the most specialized cell types in the animal kingdom with discrete distinctions from testicular sperm. The highly condensed chromatin structure, compartmentalization and lack of organelles contribute to this unique cell that lacks active transcription and translation thereby limiting cell function primarily to posttranslational modifications. Acute and transient postejaculatory sperm exposure to environmental stressors may elicit subtle phenotypes that go undetected during routine analyses, but manifest as paternal idiopathic subfertility. Until recently, insults to postejaculatory sperm were largely considered to elicit structural defects that prevented sperm transport, storage within the female reproductive tract or nuclear abnormalities resulting in failed fertilization or embryo development. However, recent evidence suggests that transient susceptibility to anthropogenic environmental stressors and acute pharmacologic exposure not only impacts sperm function, but confers epigenetic modifications with consequences on preimplantation development. Increased understanding of environmental impacts on basic sperm biology is an understudied area of research that is likely to implicate multidisciplinary aspects of early development including recreational, dietary, and pharmaceutical considerations of paternal contributions to early life.