1- to use nageotte chamber the sample should be stained with turk's solution to get best results. 2- after staining, pippetting 100 microlitter into the chamber and leave it for 15 mints. 3- under the light microscope count just the first 5 rows.. 4- use this equation to calculate the residual WBC's: (WBC's count / 5) x 1000 x blood unit volume ml ******** WBC's count = from the chamber 5 = # of counted rows 1000 = volume of mixture(100micro of sample+900 micro of turk's solution) blood unit volume= (weight of the blood unit - weight of empty blood bag) / 1.1 (specific gravity of RBC)