Mouse genetics provides insight into folliculogenesis, fertilization and early embryonic development

After colonization of the gonad, mouse female germ cells enter into the prophase of the first meiotic division as a mid-gestational hallmark of gender. Perinatally, oocytes interact with granulosa cells to form primordial follicles which, with cyclic periodicity, enter into a 3-week growth phase that culminates in meiotic maturation and ovulation. Successful fertilization in the oviduct results in the onset of embryogenesis. Genes expressed in oocytes encode maternal factors that control many of these developmental processes. The establishment of mouse models in which specific genes have been disrupted offers robust insights into molecular mechanisms that control oogenesis, folliculogenesis, fertilization and early embryogenesis. Although relatively few developmental circuits have been characterized in genetic detail, the ongoing revolution in mouse genetics holds great promise. These model systems provide novel information into the molecular basis of the pathways required for oocyte-specific processes as well as for interactions with the temporally changing environment of female germ cells. The similarities between the mouse and human genomes provide assurance that this knowledge will rapidly translate into a better understanding of human reproduction.