Responses of cell populations in vitro to toxic substances are very dynamic and exceed hours or even days. Toxicologists realise that cell-based dynamic assays can acquire important additional information about toxic responses of individual cell within a treated population.
In the past, this type of cellular dynamics could have been monitored only with the help of time-lapse microcinematography. In spite of several advantages, the time-lapse approach has been used relatively infrequently in the routine in vitro cytotoxicity assessment.
The main reasons were demanding time and work schedules, problems with quantification of visual information, and lack of mechanistic data. Recently, the situation has changed dramatically.