Programmed cell death in the germline.

In many organisms, programmed cell death of germ cells is required for normal development. This often occurs through highly conserved events including the transfer of vital cellular material to the growing gametes following death of neighboring cells. Germline cell death also plays a role in such diverse processes as removal of abnormal or superfluous cells at certain checkpoints, establishment of caste differentiation, and individualization of gametes. This review focuses on the cell death events that occur during gametogenesis in both vertebrates and invertebrates. It also examines the signals and machinery that initiate and carry out these germ cell deaths.