When using cell counters, understanding what results imply is significant. Here are some general terms used in almost every cell counter.

__Total count____ (cells/mL):__

This defines the total number of cells counted in the entire population including both live and dead cells.

When using fluorescent-based cell counters, cell-permeable fluorescent dyes such as acridine orange (AO) are used for total cell counting.

__Viable cells____: (cells/mL):__

Viable is defined as the live cells in the population.

Trypan blue only dyes the outer layer of viable cells, making it possible to distinguish between viable and non-viable cells.

__Non-viable cells____ (cells/mL):__

As the word defines itself, non-viable cells are dead cells in the population.

For non-viable cells, trypan blue dyes the entire cells including the inner membrane.

When using fluorescent-based cell counters, DAPI is used to dye only the non-viable cells. After obtaining total cells and non-viable cells, viable cells are then calculated.

Thus, calculation is as follows:

**Viable cells = Total cells - Non-viable cells**

__Viability____ (%):__

Viability is defined as the ability to live, grow, and develop (Merriam Webster). In cell counting, cell viability is the proportion of live cells in the entire population.

__Coefficient of Variation____ (%):__

This is the ratio of the standard deviation to the mean, in simpler words, the value showing how data are dispersed around the mean. Thus, the lower the coefficient of variation (CV) value, the more precise the data are as they are close together to the true (mean) value.

This value would appear in high-throughput cell counters when comparing samples in groups.

__Dilution factor____ (DF):__

When counting cells, either trypan-blue or fluorescent dye should be mixed with the cell sample. Therefore, dilution factor should be considered in the final volume of the sample because the volume of staining solution is added to the initial volume of sample.

For example, when using hemocytometer with 10 μL of sample and 10 μL of trypan blue,

DF = 20 μL (sample volume + trypan blue volume) / 10 μL (initial sample volume) = 2.

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