[Morphogenetic shift of hemoglobin types in the ontogeny of rats]

The embryonic haemoglobin represented by 4 fractions was shown to form in the nucleate erythroid cells of the yolk sac. The dynamics of their quantitative changes was determined in 10 to 14 days old embryos. Anuclear red cells of the subsequent haemopoietic centers synthesize the heterogenous haemoglobin system (fractions 1--6). It includes components such as HbF (fractions 5, 6) the maximal contents of which is timed to a later embryonic stage. Fractions 3 and 4 constitute HbA haemoglobin. These fractions were shown to differ by their resistance against acids and to be unequally distributed among the red blood cells. In the blood of foetuses and phenyl hydrasine anemic animals the amount of cells with predominance of fractions 5 and 6 increases. Under these conditions the level of alkali resistant haemoglobin also increases.