Cell Counting; Hemocytometer

Cell Counting; Hemocytometer

Example 1

Suppose a student counted 170 cells in

ten squares of a hemocytometer and did not dilute his

cells with trypan blue or additional medium. Since the

cell sample has not been combined with anything the

dilution factor is 1. What is culture’s cell concentration?

Answer

(170 cells total)(10⁴)(1) /(10 squares) = 1.7 x 10⁵ cells/mL

Example 2

Before placing a sample into the hemocytometer

a student combined 75 μL of cell suspension

with 75 μL of trypan blue for staining. If this student

counted 225 living cells in 10 squares, what is the concentration

of living cells in this cell culture?

Answer

(225 cells total)(10⁴)(2) / (10 squares) = 4.5 x 10⁵ cells/mL

Example 3

Before placing a sample into the hemocytometer

a student combined 50 μL of cell suspension

with 50 μL of trypan blue for staining. If this student

counted 350 living cells in 10 squares, (Part A) What is

the concentration of this cell culture? (Part B) If the

cell sample came from a culture with a total volume of

7.50 mL, what is the total number of cells in this culture?

Part A Answer

(350 cells total)(10⁴)(2) / (10 squares) = 7.0 x 10⁵ cells/mL

Part B Answer

(7.0 x 10⁵ cells/ml)( 7.50 mL) = 5.25 x 10⁶ cells total