How Hemocytometer Cell Counter Works

A hemocytometer is a specialized glass slide used to manually count cells under a microscope. It is commonly used in cell biology and microbiology to count the number of cells in a sample, helping to determine cell concentration. This method is essential in many experiments, including determining cell viability and growth rates.

Steps to Use the Hemocytometer

Prepare the sample by mixing the cell suspension thoroughly to ensure even distribution.
Take a small volume (usually 10 µL) of the cell suspension and place it into the hemocytometer's chamber.
Place the hemocytometer under the microscope and focus on the grid pattern. The grid is divided into smaller squares, and the cells can be counted in these squares.
Count the cells in several of the large squares (typically 5–10) and record the number of cells in each square.
Use the following formula to calculate the cell concentration in the original suspension:

Cell concentration = (Total number of cells counted) × (Dilution factor) × (Factor for hemocytometer)

Total number of cells counted: The number of cells in the selected squares of the hemocytometer.
Dilution factor: The dilution applied to the original cell suspension, if applicable.
Factor for hemocytometer: A constant based on the volume of the chamber and the area counted. For a standard hemocytometer, this factor is usually 10,000.

Example Calculation

Suppose you counted the following cells in five squares of the hemocytometer:

Square 1: 50 cells
Square 2: 45 cells
Square 3: 60 cells
Square 4: 55 cells
Square 5: 50 cells

The total number of cells counted is:

50 + 45 + 60 + 55 + 50 = 260 cells

Assuming no dilution was made and the factor for a standard hemocytometer is 10,000, the cell concentration can be calculated as:

Cell concentration = 260 × 1 × 10,000
Cell concentration = 2,600,000 cells/mL

This means that the original cell concentration is 2.6 million cells per milliliter.

Extra Tip

To improve accuracy, count cells in more squares (e.g., 10–20 squares) and take an average. This reduces the potential for counting errors. Also, make sure to use proper pipetting techniques to avoid bubbles or uneven distribution of cells in the chamber.

Example

Calculating Cell Concentration with Hemocytometer

Hemocytometer is a tool used in laboratories to count cells manually. It is often used for determining the concentration of cells in a liquid sample, such as blood or cell culture. The cell concentration can be used in various biological and medical analyses.

The general approach to calculating cell concentration with a hemocytometer includes:

Counting the number of cells in a known volume.
Using the formula to calculate the concentration of cells per milliliter (cells/mL).
Adjusting the count for the dilution factor if the sample was diluted before counting.

Cell Concentration Formula

The general formula for calculating cell concentration is:

\[ \text{Cell Concentration} = \frac{\text{Number of Cells} \times \text{Dilution Factor}}{\text{Volume of Area Counted (mL)}} \]

Where:

Number of Cells is the total number of cells counted in the hemocytometer grid.
Dilution Factor is the dilution applied to the sample before counting, if any.
Volume of Area Counted is the volume of the area of the hemocytometer where cells were counted (typically in milliliters).

Example:

If 150 cells are counted in one of the squares of the hemocytometer and the volume of the counted area is 0.1 mL, and there was no dilution applied (dilution factor of 1), the calculation is:

Step 1: Multiply the number of cells by the dilution factor: \( 150 \times 1 = 150 \) cells.
Step 2: Divide by the volume of the area counted: \( \frac{150}{0.1} = 1500 \, \text{cells/mL} \).

Counting Cells in Different Grid Areas

Hemocytometers are often divided into smaller grids, each containing a set volume. The number of cells counted in each grid is then used to calculate the concentration. The calculation might involve counting cells across multiple grid areas to increase the accuracy of the count.

Example:

If cells are counted in 4 different grid areas, each with a volume of 0.1 mL, and the total number of cells counted is 600:

Step 1: Divide the total number of cells by the number of areas counted: \( \frac{600}{4} = 150 \) cells per grid area.
Step 2: Multiply by the dilution factor (if any) and divide by the volume: \( \frac{150 \times 1}{0.1} = 1500 \, \text{cells/mL} \).

Real-life Applications of Cell Counting

Cell counting with a hemocytometer is widely used in various fields of biology and medicine, including:

Estimating the concentration of cells in blood samples.
Monitoring cell growth in culture media.
Determining the health and viability of cultured cells.

Common Units in Cell Counting

SI Unit: The concentration of cells is typically expressed as cells per milliliter (cells/mL).

Common Operations with Hemocytometer Counting

Dilution Adjustment: When a sample is too concentrated or too diluted, it may need to be diluted to bring the count within an optimal range.

Cell Viability: In addition to counting cells, the viability of cells can also be determined by using dyes like trypan blue.

Cell Culture Management: Regular cell counting is essential for managing and maintaining cell cultures, ensuring the proper conditions for growth.

Hemocytometer Cell Counting Examples Table
Problem Type	Description	Steps to Solve	Example
Calculating Cell Concentration	Determining the number of cells per milliliter in a liquid sample using a hemocytometer.	Count the number of cells in a specific grid area of the hemocytometer. Use the formula: Cell Concentration = (Number of Cells × Dilution Factor) / Volume of Area Counted (mL).	If 150 cells are counted in one grid and the volume of that grid is 0.1 mL, the cell concentration is: \[ \text{Cell Concentration} = \frac{150}{0.1} = 1500 \, \text{cells/mL} \].
Adjusting for Dilution	Account for dilution factors when the sample has been diluted before counting.	Multiply the number of cells by the dilution factor. Use the formula: Adjusted Cell Concentration = Cell Concentration × Dilution Factor.	If the sample was diluted by a factor of 2, and the cell concentration was 1500 cells/mL, the adjusted concentration is: \[ \text{Adjusted Cell Concentration} = 1500 \times 2 = 3000 \, \text{cells/mL} \].
Counting Cells Across Multiple Grids	Counting cells in multiple grid areas to increase the accuracy of the concentration measurement.	Count the cells in several grid areas. Average the counts and calculate the overall cell concentration using the formula.	If cells are counted in 4 grid areas and the total number of cells counted is 600, the average per grid area is 150 cells. The concentration is then: \[ \text{Cell Concentration} = \frac{600}{0.4} = 1500 \, \text{cells/mL} \].
Real-life Applications	Using cell concentration calculations in biological and medical research.	Assessing cell viability in culture. Monitoring cell growth rates in experiments. Quantifying the concentration of blood cells in clinical labs.	If a lab wants to prepare a cell culture with 10 million cells per mL, the hemocytometer calculation helps determine how much of the sample to add for the right concentration.