Nuclear chromatin decondensation of human sperm: a review

The decondensation of the nucleus of human spermatozoa normally occurs in the oocyte and allows the formation of a male pronucleus. This phenomenon must occur rapidly at this stage but is excluded during all the preceding stages of maturation of the sperm and during travel through the female genital tract, as otherwise it would loose its genome. The compactness of the sperm nucleus has been studied in an attempt to understand the biochemical substratum involved in the condensation/decondensation processes. This review is limited to human sperm, as the decondensation process seems, up to a point, rather different from that described in animals because of different susceptibilities to decondensing reagents and different protein ratios.