Morphology of erythroblasts derived from ES cells in vitro.

The wild-type and Alas2-null ES cells were cultured on a feeder layer of OP9 cells, and floating cells on day 8 and day 14 were collected as primitive and definitive erythroblasts, respectively. (A) The wild-type primitive erythroblasts. (B) Alas2-null primitive erythroblasts. (C) The wild-type definitive erythroblasts. (D) Alas2-null definitive erythroblasts. Original magnification, × 400 for panels A-D. (E) Cell pellet of the wild-type (left, red) and Alas2-null (right, white) definitive erythroblasts.