In the last decade the 'comet assay' or 'single cell gel electrophores
is assay' has been established as a sensitive method for the detection
of DNA damage and the measurement of its recovery. The results publis
hed in the literature have often been obtained with different methods
for comet structure measurement. In most cases these data are not comp
arable with each other. Even when using similar systems for the analys
is, it is difficult to obtain matching data. This presentation will de
scribe some technical aspects of our measurement equipment and evaluat
ion software. It focuses on necessary experimental conditions to minim
ize errors in obtaining such data. The software developed here allows
the rapid analysis of the microscopic samples (<2 a per image). The im
age analysis was designed with respect to the morphological shapes of
comet cells, which were investigated with a confocal laser microscope.
The system is built with standard components which are commercially a
vailable. As a measure of the amount of DNA damage the ratio of fluore
scence intensity was used inside the comet tail and the fluorescence i
ntensity of the comet head. Other parameters such as DNA content, come
t area, head radius, tail length and tail moment are also determined.
The reproducibility of the system has been evaluated in several experi
ments over a period of 5 years.