The kinetics of cellular proliferation in human tissues. Determination of duration of DNA synthesis using double labeling autoradiography.

The duration of the DNA synthesis period in normal and malignant human tissues from the larynx, trachea bronchus and esophagus of 13 patient has been estimated by a tritiated thymidine, carbon-14 thymidine double-labeling method in vitro. The DNA synthesis times range from approximately 10 to 25 hours, are shortest in normal tissues, and are longer in malignant tumor cells than in benign tumor cells. The double-labeling method, the analysis of thymidine labeling index data for the measurement of the S period, and a model for determining potential doubling times in human tissues are described and discussed.