A prior understanding of the microscopic anatomy of the organism can give a better understanding of how the observed CFU/mL relates to the number of viable cells per milliliter. Alternatively it is possible to decrease the average number of cells per CFU in some cases by vortexing the sample before conducting the dilution. However many microorganisms are delicate and would suffer a decrease in the proportion of cells that are viable when placed in a vortex.[citation needed]