Question

Refer to the hemocytometer drawing in Figure 1. The cell numbers refer to the total cell count in each of the numbered large squares. If the sample is undiluted and unstained, what is the cell density of the sample? (Show how you figured out your answer, and include units) Square #1: 125 #2: 135 #3: 130 #4: 135

Answer 1

This is a standard image of a haemocytometer, the boxes on the four corners are used to count the WBCs and other cells, like bacterial cells, eukaryotic cells, while thee middle square with very fine grid lines are used for counting RBCs.

In the problem as it has not been mentioned what cell is counted, we shall aassume that the cells are not RBC but any other type of cell, and the calculation would be as follows:

Volume of each large square = 1mmx1mmx0.1mm = 0.1 cu mm = 10^-4 cu cm = 10^-4ml (as 1 cc = 1ml)

Average of the total cell count the 4 large boxes = (125+135+130+135)/4 = (525/4) = 131.25

So 131.25 cells are present in 10^-4 ml, so in 1ml, 131.25 x 10^4 = 1312500 cells/ml of the solution provided