On cell contribution to gonadal soma formation in quail-chick chimeras during the indifferent stage of gonadal development.

A quail mesonephros was produced in a chicken embryo by orthotopic transplantation of quail left Wolffian duct and intermediate mesoderm between somites 18 and 21 in a 2 day chicken embryo. During the indifferent period of gonadal development in the chicken (day 4-6), no mesonephric (quail) cells take part in forming gonadal somatic cells. At this period all these cells are derived from the surface epithelium. The epithelial cells leave the surface where colonization of primordial germ cells occurs. The mesonephros begins its participation in gonadal soma formation between day 6 and 7, the time of sexual differentiation. These results are discussed in terms of sexual differentiation and the development stage of the mesonephros.