Examination and processing of human semen - libdoc.who.int ...

CHAPTER 2 Standard procedures
105
12. Report the average concentration of peroxidase-positive cells to two significant
figures.
13. Calculate the total number of peroxidase-positive cells per ejaculate (see Comments
after Section 2.18.1.8).
Fig. 2.14 Peroxidase-positive and -negative cells in human semen
A peroxidase-positive granulocyte (P) (brown colour) and a peroxidase-negative round cell (N).
Scale bar 10 m.
Micrograph courtesy of TG Cooper.
2.18.1.5 Calculation of the concentration of peroxidase-positive cells in semen
The concentration of peroxidase-positive cells in semen is their number (N)
divided by the volume of the total number (n) of grids examined for the replicates
(where the volume of a grid is 100 nl), multiplied by the dilution factor.
For a 1 + 9 (1:10) dilution, the concentration is C = (N/n) × (1/100) × 10 cells per nl =
(N/n) × (1/10) cells per nl. Thus (N/n) is divided by 10 to obtain the concentration in
peroxidase-positive cells per nl (10 6 cells per ml).
When all nine grids in each chamber of the haemocytometer are assessed, the
total number of peroxidase-positive cells can be divided by the total volume of
both chambers (1.8 l), and multiplied by the dilution factor (10), to obtain the concentration
in cells per l (thousand cells per ml).
Note: This procedure can be used to calculate round cell concentration when the
total number of round cells counted (peroxidase-positive and -negative) is used for
N in the calculation.