Effects of the removal of neural crest anlage upon endodermal morphogenesis and primordial germ cells migration in toad embryo.

The anlagen of neural tube or neural tube and neural crests were removed from toad embryos at the early neurula stage. The removal of the neural tube anlage does not affects the normal development of embryos. The removal of neural tube plus neural crest anlagen results in major disturbances of both endodermal morphogenesis and primordial germ cell migration. The possible indirect influence of neural crest cells upon the migration of the primordial germ cells is discussed. The neural crests cells could be involved in the formation and/or release of an attractive morphogen from embryonic chordomesoderm responsible for the migration of the primordial germ cells.