[Establishing of an asymmetry index in the germ cell distribution between the genital ridges in the Hubbard chick embryo].

Germ cell numberings inside the gonadic anlages of Hubbard chick embryos allowed us to display these following events: From stage 23 to stage 26, the germ cell number obviously increases. It is for this period that an asymmetry index number, specific for the Hubbard strain is got, thanks to a decreasing in the number of gonocytes colonizing the right gonad epithelium. It is for the same period that the medulla differentiates and becomes populated with gonocytes. Such simultaneous events allow us to suppose that the gonadic colonization might result from some interactions between the germinal epithelium and the underlying mesenchyme.