Production of specific granules occurs mainly during which stage of granulocyte development?
(A) granulocyte colony-forming unit
(B) metamyelocyte
© myeloblast
(D) myelocyte
(E) promyelocyte
explanation
(D) Generation of specific granules occurs during the myelocyte stage. Development of all three types of granulocytes follows a similar sequence of stages. The granulocyte colonyforming unit (choice A) is an undifferentiated progenitor cell of the granulocyte line. Buildup of the protein synthesis machinery occurs during the myeloblast (choice C) and promyelocyte (choice E) stages. The promyelocyte stage is also characterized by production of primary (nonspecific) granules. After the myelocyte stage, further condensation and reshaping of the nucleus occurs during the metamyelocyte stage (choice B).