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Erythrocyte (red cell)
- 6-8 micrometres diameter, 2 micrometers thick
- Biconcave shape with lighter-appearing cytoplasm centrally and (usually) no granules.
- No nucleus
- Common - approx 4-6 million / mm3 blood
See here for abnormal erythrocytes.
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Platelet
- 2-3 micrometres
- Gemmate from megakaryocytes - stain dark purple compared to lighter colour of erythrocytes (see pic left) with H&E / giemsa.
- No nucleus
- Common - approx 0.2 - 0.3 million / mm3 blood
- Non phagocytic - involved in clotting
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Megakaryocyte
- Found within the bone marrow rather than the blood
- Generate platelets.
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Neutrophil
- 12-15 micrometres
- Granulocyte - small very faint pink granules under H&E
- 2-5 lobed nucleus
- In the nucleus of the neutrophil of cells from
females, there may be an appendage like a little drumstick. This is the
second (inactivated) X chromosome, known as the Barr body.
- Common - approx 50-70% of leucocytes
- Phagocytic cells
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Basophil
- 9-10 micrometres
- Granulocyte - large granules staining blue/purple under H&E
- 2-3 lobed nucleus - may be hard to see due to granules.
- Rare - approx 0.5 - 1% of leucocytes
- Non phagocytic - variety of roles through secretory mediators.
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Eosinophil
- 12-15 micrometres
- Granulocyte - large pink/red granules under H&E
- 2 lobed nucleus usually but up to 4.
- Uncommon - approx 2-4% of leucocytes
- Non phagocytic. Degranulating to release toxic mediators, mostly in response to multicellular parrasites e.g. worms.
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Lymphocyte |
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Lymphocyte (small)
- 7-8 micrometres (note size in comparison to RBC)
- Possible isolated bright violet granules - light blue cytoplasm.
- Very large round or kidney shaped nucleus, usually located non-centrally.
- Common - together with large lymphocytes, approx 20-40% of leucocytes
- Most will be B or T cells. Indistinguishable with normal staining.
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Lymphycyte (large)
- 9-15 micrometres (note size in comparison to RBC)
- Possible isolated bright violet granules - plentiful transparent to light blue cytoplasm.
- Oval/bulging nucleus, somewhat looser chromatin structure than the small lymphocyte. Eccentrically placed.
- Common - together with small lymphocytes, approx 20-40% of leucocytes
- Most will be Natural Killer (NK cells). There are other subtypes not distinguishable with normal staining.
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Monocytes
- 16-20 micrometres
- No apparent granules - transparent cytoplasm with 'ground glass' appearance
- 'Horseshoe' shaped nucleus, occasionally bi-lobed.
- Uncommon - approx 3-8% of leucocytes
- Differentiate into Macrophages or dendritic cells.
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Macrophages
- Usually found in the tissue rather than in the blood
- Phagocytic
- Will be covered in more detail
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