Modern andrology: from semen analysis to postgenomic studies of the male gametes.

A male factor is implicated in about 50% of couples treated with advanced assisted reproductive techniques (in vitro fertilization [IVF] or intracytoplasmic sperm injection [ICSI]). An important function of spermatozoa is to deliver the paternal genome to the oocyte. However, neither the routine testing of male fertility potential, nor its treatment, addresses the specific mechanisms by which spermatozoal factors may impact reproductive outcome. Recently, a number of screening tests for DNA integrity have been proposed to assess sperm chromatin abnormalities. These include nonspecific DNA strand breaks, numerical abnormalities in spermatozoal chromosome content, and alterations in the epigenetic regulation of the paternal genome. This minireview discusses methods to assess the influence of the paternal genome on reproduction beyond that which can be appreciated by simple quantitative and morphologic evaluation of spermatozoa. Finally, new data on how to select the "best fit" sperm for ICSI will be presented.