Fig. 3. Increased erythroid and normal myeloid potential in precursors from TβRI^–/– yolk sacs. Yolk sacs were collected from E9.5 embryos, dispersed, and equal numbers of cells plated in methylcellulose supplemented with growth factors. Colonies were scored 6 days later. Data from three different experiments including seven litters and 11 mutant embryos. CFU, colony forming unit; Ery, erythroid; Mix, erythroid-myeloid; GM, myeloid (granulocyte–macrophage).