Promegaloblast

Promegaloblast (promegaloblastus; pro- + megaloblast) is a cell of hematopoietic tissue that precedes the megaloblast. Promegaloblasts are formed from myeloblasts during the process of erythropoiesis and differ from them in their large size, the presence of a nucleus and basophilic cytoplasm.

As the promegaloblast matures, it loses its nucleus and turns into a megaloblast, a very large erythroid cell, from which an erythrocyte subsequently develops. Thus, the promegaloblast is an intermediate stage in the process of red blood cell maturation.

Disturbances in the maturation and transformation of promegaloblasts into megaloblasts can lead to the development of megaloblastic anemia, in which cells at the promegaloblast stage accumulate in the bone marrow.