Monoblast

**Semantic type:** Cell

**Definition:** A cell derived from a myeloid progenitor cell. It differentiates into a promonocyte. It is about 12 to 20 micrometer in diameter, has a round to oval nucleus with fine, lightly dispersed chromatin and one to four nucleoli. The cytoplasm is agranular, stains moderately to lightly basophilic, and often has an intensely stained periphery and a prominent perinuclear zone. Monoblasts are found in bone marrow and never appear in the normal peripheral blood.