Page 218 - Atlas of Histology with Functional Correlations

Lymphocytes

Few visible granules in the cytoplasm are lysosomes
Vary in size from small to large, depending on function
Large lymphocytes are in the minority, about 3%, and represent activated
cells by antigens

There are B, T, and natural killer lymphocytes
Dense-staining nucleus surrounded by a narrow cytoplasmic rim
Life span is from days to months
Essential in immunologic defense of organism

When exposed to specific antigens, B lymphocytes become plasma cells in
the connective tissue
Plasma cells release antibodies to counteract or destroy invading organisms
Constitute about 20% to 30% of blood leukocytes

Monocytes

Largest agranular leukocyte characterized primarily by a kidney-shaped

nucleus
Small granules are lysosomes but not very visible with light microscope
Live in connective tissue for months where they become powerful
phagocytes
Are part of the mononuclear phagocyte system

Constitute about 3% to 8% of blood leukocytes

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