7. Blood and Bone marrow
Table 7.1. Leucocytes Version française      [7.1. Leukocytes]
Neutrophil
  • Lobed nucleus (2-6 lobes). Lobes show condensed basophilic flakes of chromatin.
  • Pale cytoplasm with fine dusty granules (less than 0.3 µm).
  • Occasionally contains deeply stained azurophilic (lysosomal) granules (0.3-0.5 µm).
  • This cell is ameboid, phagocytic and chemotactic (i.e., it responds to attractive chemical substances).
Eosinophil
  • Bilobed nucleus with partially condensed chromatin.
  • Cytoplasm contains numerous large (0.5µm or larger) orange acidophilic granules. (The cytoplasm may also contain a few azurophilic granules).
  • This cell is chemotactic, ameboid and endocytic but not phagocytic. It responds to parasitic infections and allergens.
Basophil
  • Bilobed nucleus with partially condensed chromatin.
  • The cytoplasm contains large granules of various sizes (larger than 1 µm) and shapes. These granules, which are deeply basophilic or azurophilic, have properties of mast cells.
  • This cell secretes heparin, histamin and vasodilator substances.
Monocyte
  • Large cell with a slightly indented, large nucleus containing partially condensed chromatin.
  • Abundant pale blue or lightly basophilic cytoplasm.
  • Occasionally contains azurophilic (lysosomal) granules and vacuoles.
  • This cell is chemotactic, ameboid and phagocytic, and transforms into macrophages in the connective tissue.
Medium lymphocyte
  • Spherical or ovoid nucleus containing deeply stained flaky chromatin.
  • Blue or basophilic cytoplasm containing a few azurophilic or lysosomal granules.
  • This cell belong to the immune system.
Small lymphocyte
  • Small spherical nucleus (of the size of a red blood cell) with deeply stained condensed chromatin.
  • Nucleus surrounded by a thin rim of basophilic cytoplasm free of azurophilic granules.
  • This cell is ameboid but non-phagocytic and is involved in cellular immunity (in the case of T-lymphocytes of thymic origin) or in humoral immunity (in the case of B-lymphocytes of bone marrow origin).
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