Discrimination of G1, S, and G2 cells using high-resolution TV-scanning and multivariate analysis methods.

Images of exponentially growing mouse L fibroblasts were used to test whether G1, S, and G2 cells could be discriminated by means of densitometric, geometric, textural and chromatin features. The cells were preincubated with FUdR and labeled with 3H-TdR. The definition of G1, S, and G2 was based on autoradiography used to define labeled S cells, and DNA content used to define unlabeled 2c (G1) and 4c (G2) cells. The methanol-fixed Feulgen-stained nuclei were scanned with a TV Plumbicon camera equipped with an array-processor system. Thirty-one nuclear features were calculated and stored together with the precise coordinates of each cell for later relocation and correlation with the autoradiographic data. The features were geometric, densitometric, textural and chromatin parameters of the Feulgen stained images. Feature evaluation and supervised learning were performed. When DNA content was excluded 14 textural and chromatin features were selected. By using these a correct classification of about 80% was achieved. Inclusion of DNA content and its correlates caused degeneration of performance, yielding 75% correct classification. DNA content alone gave 69% correct classification.