[Photometric measurement of cell density in microplate cultures].

A rapid technique for measuring cellular density in microplates cultures is described. Cells are stained by toluidine blue (0% to 1% acetic acid), washed in 1% acetic acid and digested by trypsin (1%) or pronase (0.1%). Absorbance rate is read in an automated spectrophotometer for microplates. The correlation coefficient between absorbance and cellular number is higher than 0.99. The measures accuracy is satisfactory in the experimental conditions used.