The orthochromatic normoblast is the last nucleated maturation stage of erythropoiesis. The orthochromatic normoblast is the first stage of the postmitotic pool of erythropoiesis. They constitute about of nucleated bone marrow cells (myelogram).
The cytoplasm of orthochromatic normoblasts is pink (acidophilic). The nucleus is compact and pycnotic. The cells measure approximately 9 µm in diameter.