Monoblast


Monoblasts are the committed progenitor cells that differentiated from myeloid stem cell in the process of hematopoiesis. They are normally found in bone marrow and do not appear in the normal peripheral blood. They mature into monocytes which, in turn, develop into macrophages.

Structure

A typical monoblast is about 12 to 20 μm in diameter, has a nuclear to cytoplasm ratio of 4:1 to 3:1, and, like most myeloid blasts, has a round to oval nucleus with fine chromatin structure. One to four nucleoli are usually visible. The nucleus can be central or eccentric and it can show evidence of indentation or folding. The cytoplasm stains moderately to lightly basophilic and may contain small azurophilic granules.

Development

The monoblast is the first stage of monocyte-macrophage maturation. The developmental stages of the monoblast are:
CFU-GM -> monoblast -> promonocyte -> monocyte-> macrophage.

Additional images