Final answer:
Some methods to count the number of cells include direct microscopic cell count, viability staining, and indirect methods.
Step-by-step explanation:
The methods used to count the number of cells include:
- Direct microscopic cell count: This method involves transferring a known volume of a cell culture to a calibrated slide called a Petroff-Hausser chamber and counting the cells under a light microscope.
- Viability staining: This method uses vital dyes like neutral red or trypan blue to stain live and dead cells. Live cells appear clear while dead cells appear red. The stained cells are then counted using a Neubauer counting chamber, electronic particle counter, or Coulter particle counter.
- Indirect methods: These methods measure cell activity by monitoring the production of metabolic products or the consumption of reactants. For example, the formation of adenosine triphosphate (ATP), biosynthesis of proteins and nucleic acids, and consumption of oxygen can all be used to estimate the number of cells.