Stimulation of haem synthesis by erythropoietin in mouse yolk-sac-stage embryonic cells.

Cultures of disaggregated cells from mouse embryos at the stage of yolk-sac erythropoiesis have been used to test sensitivity of primary erythroid cells to erythropoietin, the hormone which controls adult red cell production. Synthesis of haem was stimulated by 89% in cells of 8-day embryos, 23 % in cells of 9-day embryos and by 19% in peripheral nucleated blood cells of 12-day embryos. Differentiation of primary embryonic erythroid cells may therefore be controlled by erythropoietin in situ. The haem precursor #-aminolaevulinic acid (ALA) did not stimulate haem synthesis under similar conditions.