University of Virginia Health System

Orthochromatic Normoblast
(Orthochromatic Erythroblast)

Bone marrow aspirate smear, Wright-Giemsa stain, 1000x

Description

The orthochromatic normoblast represents the last stage of maturation of the nucleated erythroid lineage. It is only slightly smaller than a polychromatophilic normoblast, the cytoplasm is pink-orange in color and the nuclear chromatin is very condensed (pyknotic). It is at this stage that the erythroblast exits the bone marrow into the circulation as a reticulocyte, leaving behind the nucleus along with some cytoplasm and membrane. A small number of nucleated red cells are released into the circulation along with some red cells with retained nuclear fragments (Howell-Jolly bodies). Once released into the circulation, the nucleus and nuclear fragments are quickly pitted from the cell by the spleen. Thus, in the presence of normal or near-normal splenic function, neither nucleated red cells nor red cells with Howell-Jolly bodies are seen on a peripheral blood smear.

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