Name: Counting Cells with a Hemocytometer
Uploaded: 2025-06-16T13:48:41.000Z
Duration: 6 min 31 s
Description: Thousands of YouTube videos with English-Chinese subtitles! Now you can learn to understand native speakers, expand your vocabulary, and improve your pronunciation...

Basic passive voice

A hemocytometer is a device that is used for counting cells.

It's a modified microscope slide containing two identical wells or chambers into which a small volume of cell suspension is pipetted.

We have already removed 100 microliters of our cell suspension and placed it in a micro centrifuge tube.

Dilute the suspension by adding 100 microliters of TriPan Blue.

TriPan Blue is a dye that helps us distinguish between living and dead cells.

The dye passes through the membranes of dead cells so they will appear blue under a microscope.

Living cells exclude and will appear mostly clear.

Load both chambers by pipetting the suspension under the cover slip.

Now place the hemocytometer under the microscope.

Each chamber is divided into a grid pattern consisting of nine large squares.

Each square has the same dimensions and contains 10 to the negative fourth power milliliters of suspension.

The rules for counting cells sometimes differ from lab to lab.

In our lab, we count cells in the four large corner squares and the center square.

Let's count the cells in the first square. 1, 2, 3, 4, 5, 6, 7, 8.

So what about the cells that are touching the outside boundaries of the square?

In our lab, we count the cells that touch the top and left boundaries and we ignore the cells that touch the right and bottom boundaries. 9, 10.

We need to count the number of both living and dead cells.

Remember the dead cells will appear blue.

Occasionally you will see artifacts, objects or debris that appear blurry and don't have a well-defined shape.

Proper storage, cleaning and handling of the hemocytometer will minimize the number of  There are 10 viable cells and one non-viable cell in the first square.

There are 9 viable cells and no non-viable cells.

Next, let's count the bottom right square.

There are 11 viable cells and no non-viable cells.

There are 10 viable cells and two non-viable cells.

And finally, let's count the cells in the center square.

Sometimes cells will appear as clumps or small groups.

It may be difficult to determine exactly how many cells are in a group.

The method of counting clumps of cells differs from lab to lab, so be sure to follow the procedure in your lab.

There are 14 viable cells and no non-viable cells in the center square.

The total number of viable or living cells from all five squares is 54.

The total number of non-viable cells is 3.

Now that we have counted our cells, there are several calculations we need to perform.

First, let's calculate the percentage of viable cells.

Here's the formula. 54 viable cells divided by 57, the total number of cells, gives us 0.947.

Multiply by 100 and the percentage of viable cells is 94.7%.

Next, let's determine the average number of cells per square.

We divide 54 by 5 because we counted in five squares.

The average number of cells per square is 10.8 cells.

Now, let's calculate the dilution factor.

The dilution equals the final volume divided by the volume of cells.

Our final volume is 200 microliters because we started with 100 microliters of cells and added another 100 microliters of TriPAN Blue. 200 divided by 100 is 2.

Next, we need to calculate the concentration of viable cells, the number of living cells per milliliter.

The dilution factor is 2. 10.8 times 2 times 10 to the 4th power equals 216,000 cells per milliliter.

We can write the concentration using scientific notation as 2.16 times 10 to the 5th power cells per milliliter.

From our calculations, we now know the concentration of cells in our culture is 216,000 cells per milliliter and approximately 94.7% are viable living cells. www.microsoft.com