Function of the sperm nuclear matrix.

Mammalian spermatozoa contain some of the most highly compact chromatin. This is due to the DNA binding proteins, the protamines, which replace most of the histones during spermiogenesis. This chromatin, however, shares some features with somatic cell chromatin. One of these is the organization of DNA into loop domains attached at their bases to a proteinaceous nuclear matrix. Several groups have shown that the sites at which DNA associates with the sperm nuclear matrix contain chromatin structures that are linked with specific functions. Recent data also suggest that the sperm nuclear matrix plays essential roles in the paternal pronucleus of the newly fertilized oocyte, suggesting that the sperm cell provides more information to the new embryo than solely the genetic material it delivers. Here, we will review these data which together give insight into the functional significance and requirements of sperm nuclear structure.