Brain pathology (acute hypoxia and posthypoxic encephalopathy) is associated with less pronounced hyperplasia of the bone marrow erythroid stem (due to decreased count of proliferating committed precursors) and hemolytic anemia, while secretory activity of stromal cells of the hemopoiesis-inducing microenvironment is not impaired. Severe oxygen deficiency affects erythroid precursors and impairs production of functionally normal erythrocytes in the posthypoxic period.