Immunological Potential of Yolk Sac Cells

Mouse yolk sac cells on day 9 of gestation were found to elicit a GVH response, measured by enlargement of the local popliteal lymph nodes. The response cannot be attributed to contaminating maternal cells, since F1 (Balb/c x C57B1) yolk sac cells did not cause a reaction in F1 (Balb/c x C57B1) hosts. On the other hand, yolk sac cells did not elicit a detectable MLC reaction, nor did they respond to PHA or Con A. Hence, mouse yolk sac cells have the potential to express a certain limited array of immunological reactivities, before the development of embryonic thymus and liver.