7. Maturation of Neutrophils - Bone Marrow
The different cells seen in the maturation sequence of the neutrophil
are identified (100x), from a myeloblast to a segmented neutrophil.
The overall maturation scheme of the neutrophilic line consists of
nuclear shrinkage and segmentation with concurrent condensation of
the chromatin. This process begins with the formation of a
functionally immature myeloblast and culminates with the development
of a phagocytic segmented neutrophil. This maturation takes about 15
days and occurs in the bone marrow. About half of this time is spent
in the so-called "mitotic" compartment. The cells of this compartment
-- myeloblast, promyelocyte, myelocyte -- multiply (i.e., are
mitotically active) and undergo maturation. In the last stage of the
mitotic compartment, the myelocyte begins to replace its primary
(nonspecific) granules with secondary (specific) granules. The final
three cellular stages of maturation comprise the so-called "storage"
compartment. Cells in this pool consist of metamyelocytes, band
neutrophils, and segmented neutrophils or "polys" (polymorphonuclear
neutrophils). When are these cells released into the blood?
Answer
