11 Genetic Control of Mammalian Female Meiosis

Abstract

This chapter discusses the control of chromosome segregation during mammalian female meiosis. It emphasizes the complexities of mammalian meiosis and differences between male and female mammals. As in mitotic cells, the meiotic process is subject to checkpoint control mechanisms that regulate cell cycle progression. The meiotic process in females requires additional cell cycle controls to ensure arrest at two independent points in the cell division because, with few exceptions, mammalian female meiosis is characterized by a protracted arrest at prophase of the first meiotic division (MI) and a subsequent arrest at metaphase of the second meiotic division (MII). In the majority of mammals, mitotic proliferation of oogonia is limited to the prenatal period, and all oogonia enter meiosis before or shortly after birth. The prenatal differentiation of germ cells has been best characterized in the mouse: the germ cell lineage is thought to be established during early gastrulation, when an estimated 40 or so cells are segregated to the extraembryonic mesoderm. Animals carrying targeted disruptions of DNA mismatch repair genes as well as of other genes known to play a role in meiosis in lower eukaryotes provide the first of the long awaited mammalian meiotic mutants.