metamielocito

Metamielocito is a term used primarily in veterinary and medical pathology to denote an intermediate stage of granulocytic development in the bone marrow and peripheral blood. The cell originates from myeloblasts and precedes the band stage of neutrophil maturation. In Spanish medical literature, “metamielocito” corresponds to the English “metamyelocyte.” It is characterized by a nucleus that is indented or lobulated yet not fully segmented, a granular cytoplasm, and a size intermediate between myelocytes (segmented neutrophil precursors) and band cells. Occasionally metamielocitos may be present in peripheral blood, indicating a left shift associated with acute inflammation, infection, or bone marrow stress.

During hematopoiesis, myeloblasts differentiate into promyelocytes, myelocytes, then metamielocitos before becoming band cells. The metamielocito stage is marked by cytochemical activity, particularly in myeloperoxidase and lysozyme staining, reflecting the cell’s readiness to become a fully functional neutrophil. The presence of metamielocitos in peripheral smears is usually interpreted as a sign of rapid neutrophil turnover, a common response to bacterial endotoxin exposure, or an underlying myeloproliferative disorder.

Clinically, the quantitative assessment of metamielocitos in a complete blood count (CBC) and differential is used to evaluate the bone marrow’s capacity to respond to infection. An elevated percentage may suggest a “left shift” and can be correlated with systemic inflammatory response syndrome (SIRS) or sepsis. Conversely, a paucity of metamielocitos could indicate impaired granulopoiesis, often seen in aplastic anemia or bone marrow suppression caused by chemotherapy.

In pathology reports, metamielocitos are often described in relation to other myeloid precursors. Their identification helps pathologists gauge the maturity of circulating neutrophils and to differentiate reactive processes from clonal myeloid disorders. The term remains in routine use within Spanish‑speaking medical communities, but in English‑language literature it is usually replaced by “metamyelocyte.”