Scientists have found fox13 gene that acts as a switch and controls whether germ cells eventually become sperm or eggs.
New experiments in the Japanese rice fish could help researchers learn more about how the sexual fate of germ cells is determined during vertebrate development.
Toshiya Nishimura and colleagues demonstrated that fox13, which is expressed in germ cells but not in the surrounding cells of the fish's reproductive organs, provides a molecular cue that prevents the start of sperm formation.
When the researchers disrupted fox13 in adult fish with two X chromosomes (the female state), sperm formed in the female ovary. These sperm were functional and could fertilize eggs normally.
The results indicated that germ cells in these fish, and potentially other vertebrates, do not need to be in the environment of the male reproductive organ to begin their switch into sperm.