Basic and Clinical Aspects of Sperm Chromomycin A3 Assay

Semen quality is conventionally determined according to the number, motility, and morphology of spermatozoa in an ejaculate. In turn, it is generally accepted that an association exists between these semen parameters and fertilizing ability. With the advent of in vitro fertilization (IVF) and related techniques such as intracytoplasmic sperm injection (ICSI), it has become increasingly apparent that the number, motility, and morphology of spermatozoa are not always indicative of a male’s fertility status. Methods exploring sperm DNA stability and integrity have been applied during the last decade to evaluate fertility disorders and to increase the predictive value of sperm analysis for procreation in vivo and in vitro. It has been shown that infertile men have an increased sperm histone–protamine ratio compared to fertile counterparts. This alteration of histone–protamine ratio, also called abnormal packing, increases susceptibility of sperm DNA to external stresses due to poorer chromatin compaction. Recent studies have also underlined the link between protamine deficiency and sperm DNA damage that resulted in poor fertilizing capacity.