Nature of the multipotential cells in the displaced rat yolk sac

The nature and origin of the proliferating cells were studied in displaced visceral yolk sac in vivo and in organ culture in vitro. By ultrastructural examination and reactivity with antibodies against intermediate filaments it was shown that the poorly differentiated cells which appear in this membrane have features in common with visceral endodermal cells. Using plant lectins reacting with the rat visceral endoderm (DBA, PNA, SJA and BSA-1) it was demonstrated that the proliferating endodermal cells retrodifferentiate to earlier stages of endodermal development.