Fetal hemopoiesis in diffusion chamber cultures: II. Cell proliferation and differentiation

The growth and differenciation of hemopoietic cells from murine fetal liver (FL) and adult bone marrow (ABM) in diffusion chambers (DC) implanted into normal CF1 mice were evaluated. Initially FL suspensions were approximately 90% erythrocytic, but after 4 days in DC implanted into either normal or phenylhydrazine (anemic) pretreated hosts, growth was essentially restricted to the granulocyte-macrophage cell types. The number of in vitro colony forming cells (CFC), as assayed in a double layer soft-agar technique was determined after varying periods of growth in DC of both ABM and FL. Both groups showed a progressive decline in CFC number. FL and ABM CFC generated the same proportion of different morphologic types of soft agar colonies. After 7 days of DC culture, there was a decrease in the proportion of macrophage colonies from both groupes. During DC culture the ratio of clusters (3-50 cells to colonies progressively increased in both groups suggesting a parent-progeny relationship between CFC and cluster forming cells. The results of these studies provide further evidence that the environment rather than properties intrinsic to murine stem cell determines the pattern of proliferation.