McMaster Egg Counting Chamber

Created by Karen Darley, Modified on Mon, 6 May at 10:36 AM by Kathleen Patrick


Worm egg Counting Slide for use in the estimation of HELMINTHIC infections in faecal suspensions:

Slide = 76 x 32mm
Platforms = 4mm wide
Plain Glass Top = 52mm x 17.5mm cemented on 2mm up from lower edge of slide

The cell depth of 1.5mm must be accurate. The underside of top cover is to be ruled with 1 x 10mm squares and with 10 equal distant vertical lines forming a 10mm square with 10 equal vertical columns.

The 10mm square is to be in the centre of each cell. The cells are to be open at top and bottom.

Method of use:

Under 2/3 objective of the microscope all eggs are counted which lie within the lined centimetre square of the counting chamber. Each egg counted represents '100 eggs per g' of faeces. This calculation is based on the fact that the depth of chamber is 1.5mm and consequently the volume of fluid examined is 0.15ml, which is 1/300 of the original volume of 45mls, made up of 42ml of saturated salt solution and 3g of faeces. Therefore each egg counted represents 300 per 3g of faeces, which is equivalent to 100 per g. Where two chambers are employed the total count is multiplied by 100 and divided by 2.


Clean by immersion in warm water or in the most dilute solution of a neutral detergent cleanser. Sterilisation prior to cleaning may be by immersion in alcohol, if suitable, or by immersion in a 2% solution of glutaraldehyde.

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