Red Cell Characteristics Related to Color

Polychromasia

  • The large cell in the center of this field is slightly blue/gray and is an example of a polychromatophilic red cell.
  • Increased numbers of these cells, (approximately 2 or greater per oil immersion field,) indicate increased red cell output by the bone marrow. Polychromatophilic cells are larger and younger than mature red cells, and may be larger than 9 micron in diameter. Under normal conditions, these young red cells remain in the bone marrow one or two days before release into the bloodstream. However, when the bone marrow is stressed due to blood loss or other conditions, these cells are prematurely released into the blood, resulting in a blood smear with polychromasia. These red cells are often referred to as shift cells. If stained with a supravital stain, they would be identified as reticulocytes.

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