Origin and destination of the median germ cells in late somite stage and early post-somite stage duck embryos.

In continuation of preceding investigations, in 184 duck embryos of the developmental stages 18-27 according to Hamburger and Hamilton (about 85-140 hours of incubation) a study was done on the occurrence of median germ cells. These cells proved to be present in proportionally small numbers in the stages 19-26. Their numbers were independent of the sex of the embryos and did not show any relations whatever with changes in the numbers or distribution of the intragonadal germ cells. The temporary occurrence of the median germ cells could be shown to be due to the movement of the gonadal primordia from the splanchnopleure of the yolk sac to the ventro-medial surface of the mesonephros, and it was argued that ultimately all these germ cells reach the right of left gonad.