Programmed cell death of primordial germ cells (PGCs), which is essentially complete by stage 12 of embryogenesis in wild type, is disrupted in mutant embryos; the total average number of PGCs is normal in the mutants at stage 10, but although there is a gradual reduction in the number of PGCs, it is decreased compared to wild type, such that at stage 14 the average number of PGCs is higher in the mutant embryos compared to wild type.

Although PGCs are able to incorporate into the gonad in mutant embryos, many germ cells ectopic to the gonad are seen at stage 14.