An electron microscopic study of erythropoiesis in fetal and neonatal rabbits

This investigation records the chronology of events relating to erythropoiesis in the late fetal and early neonatal rabbit. The formation of the marrow cavity in the rabbit femur and the changing cell population in the extravascular spaces are described for the period from day 24 of gestation to 8 weeks postpartum. In the fetal liver, erythropoiesis is shown to occur in typical red cell islands. As hepatic red cell production declines, lipid accumulates in the liver, much as fatty infiltration of marrow follows reduction of erythropoiesis in the marrow. The spleen appears to have erythropoietic potential although it does not normally contribute to red cell production in this animal. The spleen also appears to serve as a storage site for large numbers of platelets in the developing rabbit.