Medical Laboratory Scientist (MLS) ASCP Practice Exam

A monoblast is a specific type of white blood cell that serves as a precursor to monocytes. In the process of hematopoiesis, monoblasts are derived from stem cells in the bone marrow and undergo several stages of differentiation, eventually maturing into monocytes, which play a crucial role in the immune response by engulfing pathogens and dead cells.

Monoblasts are characterized by their large size, abundant cytoplasm, and distinctively shaped nucleus that is typically oval or kidney-shaped. Understanding this cell type is vital for recognizing the various stages of myeloid cell development in blood cell formation and for diagnosing related hematological disorders.

The other cell types listed do not represent monoblasts. Erythrocytes are red blood cells responsible for oxygen transport. Promyelocytes are an earlier stage in the development of granulocytes, specifically a precursor to myelocytes, and myeloblasts are precursors to granulocytes, which include neutrophils, eosinophils, and basophils. Therefore, knowing the specific lineage and roles of these cell types highlights why the identification of monoblasts is key in the context of hematology.