Hemocytometer

Hemocytometer with gloved hand

Hemocytometer

Haemocytometer Grid

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Haemocytometer side

Hemocytometer grid 100x

Hemocytometer

A hemocytometer is a laboratory instrument used to count the number of cells in a liquid sample. It is commonly used in biology and medicine to quantify cell concentrations in blood samples, as well as in the study of other bodily fluids and in various industrial applications, such as in the brewing industry to count yeast cells. The device consists of a thick glass microscope slide with a grid of precisely etched lines. When a liquid sample is placed on the grid, cells within the sample settle on the grid lines, allowing for an accurate count under a microscope.

History

The hemocytometer was invented in the late 19th century by Louis-Charles Malassez, a French physician. It was initially developed to count blood cells, particularly red blood cells, in clinical settings. Over the years, the design and functionality of the hemocytometer have evolved, but its basic principle remains the same.

Design and Function

The traditional hemocytometer design includes a thick glass slide with two chambers, each chamber having a grid etched into its surface. The grid is usually divided into multiple counting areas, and each area is further subdivided into smaller squares of known dimensions. This precise grid allows for the calculation of cell concentration in the sample being examined.

To use a hemocytometer, a diluted sample of the liquid containing cells is placed on the grid. A coverslip is placed over the sample to ensure an even spread of the liquid across the grid and to avoid evaporation. The sample is then viewed under a microscope. The cells that fall within the boundaries of the designated squares are counted manually. The number of cells counted is then used to calculate the concentration of cells in the original sample, taking into account the dilution factor and the volume of liquid over the grid.

Applications

The hemocytometer is widely used in various fields for different purposes:

• In medicine, it is used to count blood cells in hematology, to monitor cell counts in patients undergoing chemotherapy, and to count sperm in fertility clinics.
• In biology, it is used in cell culture to determine the concentration of cells before experiments.
• In the brewing industry, it is used to count yeast cells to ensure the correct concentration for fermentation.
• In environmental science, it can be used to count microorganisms in water samples.

Advantages and Limitations

The main advantage of using a hemocytometer is its simplicity and the ability to obtain quick results without the need for expensive equipment. However, the accuracy of the counts can be affected by human error, the quality of the sample preparation, and the precision in applying the sample to the grid. Additionally, counting large numbers of samples can be time-consuming and tedious.

Conclusion

The hemocytometer remains a fundamental tool in both clinical and research settings for counting cells. Its design has stood the test of time, providing a simple yet effective method for quantifying cell concentrations in a variety of samples.