Hemoglobin ontogeny during normal mouse fetal development.

Pure populations of large, nucleated erythrocytes derived from yolk sac blood islands were obtained during normal fetal mouse development. Embryonic hemoglobins were present in these cells early in gestation. Later in gestation, an increasing amount of adults hemoglobin was also synthesized and accumulated in this population of primitive nucleated erythrocytes, as demonstrated by both biochemical and immunocytochemical techniques.