26295C

26295C
Caption: Human red blood cells, activated platelets and white blood cells - T lymphocyte (yellow) and granulocytes (green). White blood cells (leukocytes) are important in cellular defense in the human body. Human T lymphocytes (T cells) are involved in the specific immune response and are composed mainly of precursor T cells and B cells (pre-T cells and pre-B cells). Pre-T cells and pre-B cells are subsets of lymphocytes that originate in the red bone marrow from hematopoietic stem cells. Pre-T cells circulate in the blood before migrating to the thymus where they develop into specialized cells (helper T cells and killer T cells) that are able to identify antigens and infected tissue. Granulocytes (neutrophils) are leukocytes with granules in their cytoplasm that contain destructive chemicals. Neutrophils are involved in inflammation and other immune responses. They assist in cellular defense (phagocytosis) of pathogenic microorganisms. Neutrophils travel from a capillary to infected regions where antibody / antigen complexes are located. A neutrophil destroys an antigen by engulfing it and injecting lethal chemicals. Macrophages will arrive later to consume any remaining debris. Neutrophils are involved in cellular defense (phagocytosis) of small pathogenic microorganisms.
Magnification*: x1,000
Type: SEM
Copyright 2007 Dennis Kunkel Microscopy, Inc.
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