MECHANISMS OF NONDISJUNCTION IN MAMMALIAN MEIOSIS

This chapter discusses the mechanisms of nondisjunction, with regard to the origin of aneuploidy, in mammalian germ cells at the molecular, cellular, and tissue levels. Developing germ cells appear to be especially sensitive to any environmental insult or to a chromosomal constitution that induces perturbations in the highly ordered timing of events in meiotic progression. The interactions of germ cells with their supporting tissues may be one of the factors that decides meiotic success rate, as it may influence the kinetics of the initial phases of the cell cycle, particularly the S-phase. A delay in synapsis and recombination may delay the pairing and repair of DNA breaks and may trigger the meiotic arrest and atresia at the end of the meiotic prophase. However, germ cells that escape this quality control may have increased risks for nondisjunction as the early disturbance in the cell-cycle progression may also affect distal meiotic events. © 1994 Academic Press Inc.