[Organizing the sperm nucleus]

Thanks to the success of new assisted reproductive technology, including sperm microinjection (i.c.s.i.), men with severe spermatogenesis impairments can now become biological fathers. Whether the germinal cell used for i.c.s.i. is conveying appropriate genetic and epigenetic information is an important concern. However, to date, there is a huge lack of data on which information is epigenetically conveyed to the offspring and how. The basic support for epigenetic marks is the nucleus structure. During spermatogenesis, a major re-organization of the male germ cells nucleus structure occurs, which includes a global condensation associated with a removal of most core somatic histones and their replacement by sperm-specific nuclear proteins. The available data on the molecular mechanisms involved in this process and how it could relate to the setting of male-specific epigenetic information is reviewed and discussed in light of our current knowledge about nuclear structure and functions.