ABSTRACT
Embryonic/fetal hepatic erythropoiesis is commonplace in mammals, a difference that is potentially ascribable to the existence of a large yolk sac in birds offering a location for extended hemopoiesis as opposed to the reduction of this organ to a rudimentary condition in mammals. The embryonic chick’s spleen briefly produces some granulocytes along with relatively fewer erythrocytes. Hemocytoblasts expressing their typical round shape, large nucleus, prominent nucleolus and thin ring of basophilic cytoplasm were first evident at E8 and became increasingly abundant up till day E12. This group found that the evolution of erythropoiesis was morphologically best followed in imprint preparations. On consideration of its overall limited erythroproductive activity, Danchakoff concluded that the normal embryonic chick spleen is not an active erythropoietic organ although it has the potential to be one. The thymus of the chick embryo is cited as second only to the bone marrow in leukopoietic activity.
