The McGill Physiology Virtual Lab

Blood Laboratory

Blood cell indices > White cell count
  The procedure for total white cell count proceeds in exactly the same manner as that described for red cell count except for a different dilution factor (1:20 dilution) and composition of the dilution fluid. The diluent contains an agent (glacial acetic acid) which lyses the red cells, allowing a proper count of white cells.
Review the use of the hemocytometer and the use of the adjustable pipette.

Observe the grid of the hemocytometer below. White blood cells are counted in the areas coloured blue (4 corners). Consider the following: One corner grid of 16 squares is 1mm x 1mm in area and 0.10 mm deep. The dilution factor is 1:20. How would you convert the number of white blood cells that are counted in the four corner squares to the total number of white blood cells/Ál? (N.B. 1 Ál (microliter) = 1 cubic mm )

How do I do this?

Click here to open a window which mimics what you might see looking through the 10x objective of the microscope. Only one blue corner of the grid shown above is visible. Count the white cells in the sixteen squares and determine the total white cell count. Note that here you are counting in only one of the corners, and that normally you would count in all four. Note also that a lot of debris is present on the slide, due to the lysing of red cells to allow for a proper white cell count. In a real laboratory session, one would examine "uncertain" elements with higher magnification to confirm that they are white cells.
The expected range for white cell count in both males and females is as follows:
4,000-11,000 /Ál

To continue with the next section, Differential white cell count, click here