RT Book, Section A1 Kuijpers, Taco A2 Kaushansky, Kenneth A2 Prchal, Josef T. A2 Burns, Linda J. A2 Lichtman, Marshall A. A2 Levi, Marcel A2 Linch, David C. SR Print(0) ID 1180444514 T1 Structure and Composition of Neutrophils, Eosinophils, and Basophils T2 Williams Hematology, 10e YR 2021 FD 2021 PB McGraw-Hill Education PP New York, NY SN 9781260464122 LK hemonc.mhmedical.com/content.aspx?aid=1180444514 RD 2024/03/28 AB SUMMARYEarly in precursor development in the marrow, cells destined to be leukocytes of the granulocytic series—neutrophils, eosinophils, and basophils—synthesize proteins and store them as cytoplasmic granules. The synthesis of primary or azurophilic granules defines the conversion of the myeloblast, a virtually agranular, primitive cell that is the earliest granulocyte precursor identifiable by light microscopy, into the promyelocyte, which is rich in azurophilic granules. Synthesis and accumulation of secondary or specific granules follows. The appearance of specific granules marks the progression of the promyelocyte to neutrophilic, eosinophilic, or basophilic myelocytes. Thereafter, the cell continues maturation into an amitotic cell with a segmented nucleus, capable of chemotaxis, phagocytosis, and microbial killing. The mature granulocytes also develop cytoplasmic and surface structures that permit them to attach to and penetrate the wall of venules. Most is known about neutrophilic granulocytes. These cells enter the blood from the marrow, circulate briefly, and move to the tissues to carry out their major function of host defense. Blood neutrophils exhibit the capacity for changes in phenotypic characteristics and lifespan depending on the stimulating milieu of cytokines and chemokines. Gene expression profiling and proteomics studies indicate the neutrophil is a transcriptionally active cell that loses much of their transcriptional and metabolic pathways during development but still keeps part of or even gains the capacity to perform its effector functions, being responsive to environmental stimuli, to perform the appropriate innate immunity roles to eliminate bacterial and fungal pathogens.