Macrocytes

MACROCYTES, MICROCYTES. Macrocytes (from Greek makros- large and kytos- cell), young red blood cells, 10-12 μ in size, larger than normal erythrocytes. Macrocytes are very often polychromatophilic and have basophilic granules. Unlike megalo-cytes, macrocytes contain vital granules. Often, remnants of the nucleus in the form of Jolly bodies (see Jolly bodies) and chromatin granules can be found in macrocytes. Macrocytes usually contain more Hb than normal erythrocytes. Macrocytes are formed in the bone marrow from larger erythroblasts; therefore, the presence of macrocytes in the blood indicates strong irritation of the bone marrow. Naegeli considers that macrocytes are formed in the blood itself by the swelling of inadequate normocytes in protein-poor plasma. Macrocytosis is observed mainly in pernicious anemia, leukemia, and some forms of childhood anemia. Microcytes (from Greek mikros- small). Very often, along with macrocytes, microcytes are present in the blood—erythrocytes 4-6 μ in size, smaller than normal (see also Anisocytosis). Microcytes originate in the bone marrow from small erythroblasts or in the bloodstream during the breakdown of erythrocytes. Microcytes formed by the latter method are very small (1-2 μ) and are called schizocytes. Microcytes are usually poor in Hb; their presence in peripheral blood is characteristic of hypochromic anemias. Microcytes are found in all secondary anemias (in malignant tumors, nephritis, hemorrhages), chlorosis, and in large quantities in hemolytic jaundice. Microcytosis is also observed during starvation, febrile conditions, and exposure of the body to high temperatures.