[Regularities of hemopoietic development in bone marrow erythroblastic islands during early ontogenesis]

Erythroblastic islands (EIs) of the bone marrow are multicellular associations of erythroid and macrophage cells. EIs serve as morpho-functional units of erythropoiesis. Erythropoiesis was studied in the rat liver, spleen, and bone marrow on days 1, 3, 7, 10, 15, and 30 after birth. Changes in the number of EIs and in their composition were simultaneously examined. After birth, erythropoiesis was shown to decrease in the liver and spleen, but it became more active in the bone marrow. There were islands of nondifferentiated hemopoietic cells on day 1 after birth, mixed hemopoietic islands on day 3, and a drastic increase in bone marrow EIs on day 7. On day 30, the levels of EIs were the same as in adult rats. There was a close relationship between the number of EIs and that of erythroid cells in the bone marrow, as well as the count of red blood cells. The age-specific dynamics of quantitative and qualitative changes in EIs and erythropoiesis is presented.