In vivo induction of granulopoiesis in visceral yolk-sac cells by foetal hepatic factors.

In order to evaluate the hypothetical activity of foetal hepatic factors on putative yolk-sac haemopoietic stem cells we used the Double Diffusion Chamber (DDC) techniqUe. The DDC were made of a regulator compartment, where foetal hepatic tissue was introduced and a test compartment where visceral yolk-sac cells were cultured. In this system a hepatic signal induced the yolk-sac stem cells to differentiate along the granulocytic pathway but did not stimulate yolk-sac CFUs growth. Contrary to CFUs originating from foetal liver or adult bone marrow, yolk-sac CFUs do not increase numerically in diffusion chamber culture.