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1. Haemocytometer

Cell Calculations 1 — Haemocytometer

 
The data provided are from microscopic observations using a haemocytometer. Estimate the number of cells in a given volume of the original culture.
(For simplicity we ignore the fact that samples from high-density cultures are generally diluted before addition to the haemocytometer chamber.)

No. cells in original volume:   x 106   
 
A general approach to these calculations is:
  • Determine the volume of the haemocytometer, which will be in mm3.
  • Convert this to cm3, the units of volume of the culture medium.
  • Determine the concentration of cells in the chamber by dividing the number observed by the volume of the chamber.
  • Then multiply by the original volume of the medium to get the total number cells.
Here is a specific example:
  • 20 cells observed in the haemocytomer above from a sample volume of 5 cm3
  • Vol of chamber = 1 mm x 1 mm x 0.02 mm = 0.02 mm3
  • 1 cm3 = 1000 mm3 ∴ vol = 2 x 10–5 cm3
  • ∴ concentration = 20/(2 x 10–5) = 106 cells per cm3
  • ∴ number in 5 cm3 = 5 x 106 cells