ABSTRACT
Yeast forms one of the important subgroups of fungi. Although most fungi have relatively complex morphology, yeast is distinguished by its usual existence as single, small cells 5–30 µm long and 1–5 µm wide. The hemocytometer gives the total cell count, both dead and viable. To distinguish between dead and viable cells, the sample is diluted with a particular stain, such as methylene blue. This staining method is also known as dye exclusion staining. It uses a diazo dye that selectively penetrates cell membranes of dead cells, coloring them, but is not absorbed by the membranes of live cells and the live cells are not stained. The advantage of using a hemocytometer is that it is quite cheap and fast. This makes them the preferred counting method in fast biological experiments in which it needs to be merely determined whether a cell culture has grown as expected.
