Different types of blood cells in bone marrow
There are different types of blood cells in the bone marrow:
Erythrocytes
The erythrocyte is a complex cell. The membrane is composed of lipids and proteins, and the interior of the cell contains metabolic machinery designed to sustain the cell through its 120-day life span and maintain the integrity of hemoglobin function. Each component of red blood cells may be expressed as a function of red cell volume, grams of hemoglobin, or square centimeters of cell surface. These expressions are usually interchangeable, but under certain circumstances each may have specific advantages. However, because disease may produce changes in the average red cell size, hemoglobin content, or surface area, the use of any of these measurements individually may, at times, be misleading.
Neutrophils, Eosinophils, and Basophils
In the normal adult human, the life of granulocytes is spent in three environments: marrow, blood, and tissues. Marrow is the site of differentiation of hematopoietic stem cells into granulocyte progenitors and of proliferation and terminal maturation. Precursor cell proliferation, which consists of approximately five divisions, occurs only during the first three stages of maturation (blast, promyelocyte, and myelocyte). After the myelocyte stage, the cells are no longer capable of mitosis and enter a large marrow storage pool from which they are released into the blood where they circulate for a few hours before entering tissues.
Monocytes and Macrophages
Monoblasts and promonocytes are the precursors of monocytes, bearing finely dispersed nuclear chromatin and nucleoli when observed in the stained film of the blood or marrow. The monoblast is a very low prevalence marrow cell, indistinguishable by light microscopy from the myeloblast. Promonocytes are 12 to 18 m in diameter (as measured on dried blood films) and have characteristic deeply indented, irregularly shaped nuclei with condensed chromatin, and numerous cytoplasmic microfilaments.
Lymphocytes and Plasma cells
ymphocytes are a heterogeneous collection of cells that can be distinguished from other leukocytes by their characteristic morphology. Blood T and B lymphocytes are indistinguishable by light and electron microscopy. Natural killer cells tend to be larger cells with relatively large granules scattered in their cytoplasm. B cells can mature into plasma cells upon activation by engagement with antigen or with certain B-cell mitogens.