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Examining CSF Using the Hemocytometer, continued

  • White cells are less refractile than red cells and appear somewhat granular. In general, white cells will be larger than red cells. However, an additional procedure beyond unstained bright-field microscopic visualization of the cells may be necessary to distinguish RBCs from other cells. This will be discussed on the next page.
  • If cells are counted in the four corner squares and the center square on both sides of the hemocytometer, the number of cells counted equals the number of cells/mm3 which is the equivalent of cells/µL.
  • The ruled area of one side of a hemocytometer is shown on the right, marked with routine counting squares for red and white cell counts. Each large square is 1 mm2 by 0.1 mm (chamber depth). If the four corner squares that are marked "W" in the image and the entire center square are counted on both sides of the hemocytometer, the area is equal to 10 square millimeters (10 mm2) and the total volume is 1 mm3(10 mm2 x .1 mm= 1 mm3, or 1µL).
  • The standard Neubauer counting chamber formula shown below is used to perform manual cell counts.