Using a haemocytometer

Using a haemocytometer

A haemocytometer is a special counting chamber designed for counting blood cells. The measurements of it are 3mm x 3mm. The haemocytometer has a central chamber with two grooves each side of it, these are 0.1mm deep. In the centre of the grid there are some triple lined squares. These squares measure exactly 1mm x 1mm. This square has 25 smaller squares inside it each measuring 0.2mm x 0.2mm. A blood sample is entered via a pipette below the cover slip.

Haemocytometer's can be used to measure the concentration of erythrocytes and leucocytes in the blood. Before blood cells can be counted they need to be diluted. This is so we can see individual cells instead of clumps of cells. If there are clumps of cells, we wont be able to see a whole cell. And also wont be able to count them. Using Dacie's fluid you dilute the cells ( 200x for erythrocytes and 20x for leucocytes). We dilute red blood cells more than white blood cells because there is a much higher frequency of red blood cells so more solution would be needed to dilute it.

Erythrocytes - Place the diluted blood sample on the haemocytometer. Count the cells in 5 of the 25 squares and take an average. Sometimes cells lie on the triple lined squares. In…