An automated method for autoradiographic analysis of cultured Schwann cells

A semi-automated analysis system based on video image analysis was developed to count labelled and unlabelled nuclei of Schwann cells which had been exposed to tritiated thymidine followed by processing for autoradiography. A Model 3000 Image Analysis system (Image Technology Corporation, Deer Park, NY) was used to acquire and process the images and provide quantitative measurements based on the distinctive size and shape of the Schwann cell nucleus. The maximum and minimum dimensions for the labelled and unlabelled nuclei were determined. These stored dimensional parameters were then compared with the dimensions of a given field of cell nuclei by the image analysis system. The counts from various fields were collected until a total of 1000 labelled and unlabelled nuclei had been analyzed. A labelling index (LI = ratio of labelled cells to total cells X 100) was then calculated and printed by the system. LIs of autoradiographs determined by automated analysis correlated well with those determined by visual cell counting. The principle of the image analysis program as described here is applicable to other systems for the measurement of LIs of a particular cell type in a mixed population. This automated process eliminates both the subjectivity and fatigue of visual counting and facilitates the rapid measurement of the LI of large numbers of autoradiographs with precision.