University of Virginia Health System

Promyelocyte
(Progranulocyte)

Bone marrow aspirate, Wright-Giemsa stain, 1000x

Description:

On a Wright-Giemsa stained bone marrow aspirate as viewed by light microscopy, the promyelocyte is the earliest identifiable cell in the granulocyte lineage. From this stage, the promyelocyte can differentiate into the neutrophilic (most), eosinophilic or basophilic lineages. It is the largest cell of the various stages of granulocyte maturation, and is distinguished from a blast by the appearance of variable numbers of primary granules in the cytoplasm and the development of the Golgi apparatus. Primary granules may appear before the Golgi apparatus is seen. The granules are coarse and range in color from azurophilic to dark blue. The nuclear chromatin is coarse but evenly dispersed and one or more nucleoli are usually seen.

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