HEMATOPOIESIS 07

Bone marrow smear. The cell labeled "B" is a promyelocyte. This is the first cell in the myeloid lineage that shows granules. The granules are primary granules (also called azurophilic granules). At this stage, we cannot assign a final differentiation fate (neutrophil, eosinophil or basophil) because there are not yet any secondary granules detectable. The cell labeled "A" is also probably a promyelocyte because we still seen a few of the primary granules. This cell is further along the differentiation pathway and the concentration of primary granules has been diluted by successive cell divisions. If we could reliably identify secondary granules, we would call this cell a myelocyte.

Neither the slide nor the objective lens used is known.