Organization of chromosomes during spermatogenesis and in mature sperm

Abstract

One of the prominent features of male germ cell differentiation is a profound sequential, structural, and spatial reorganization of the chromosomes, which manifests in diverse events, such as chromatin remodeling, DNA recombination and repair, dynamic movements of chromosomes, and chromosome domains (centromeres and telomeres) within the nucleus. Divergent states of male germ cell chromosomes during proliferation, meiosis, and final differentiation to sperm are accompanied and supported by unprecedented in-scale changes in the chromatin protein composition. It is known that in interphase somatic cell nuclei, each chromosome occupies a defined chromosomal territory (CT), whose position is nonrandom. Despite dramatic changes during spermatogenesis, the principle of nonrandom CT positioning is preserved in sperm. A specific feature of sperm chromosomes is their extraordinary compactness and hairpin structure. A distinctive feature of sperm chromatin is its tripartite organization supported by protamines and two pools of residual histones. We propose that the combination of these unique features plays a role during male pronucleus formation after fertilization. © Springer-Verlag Berlin Heidelberg 2011.