Abstract

Cell turnover time varies from one tissue to another but is reproducible as a hereditary characteristic for a given cell line. The present study indicates that it is prolonged in the lungs of mice congenitally predisposed to developing primary lung tumours. Primary malignant tumours occur more frequently in areas of relatively slow cell replacement in the human gastrointestinal tract than in those where cell turnover is rapid. On the basis of these observations it is suggested that postmaturity of a cell may be a significant factor in the development of neoplastic change.