Cell proliferation of the normal esophagus of mice harbouring a squamous cell neoplasia in the uterine cervix.

Some human tumors have been found to induce proliferative lesions in the squamous epithelium in organs remote from the primary tumor. This phenomenon was explored in the present animal model. After a single injection of 3H-thymidine, the proportion of DNA synthesizing basal and parabasal esophageal cells as well as the pace of intraepithelial cell migration was assessed in 124 C57Bl mice. The uterine cervix of 57 animals had been painted topically with 3,4 benzo(a)pyrene for 5 months, or with the vehicle acetone (44 animals), while 23 animals remained untreated. Groups of animals were killed from 8 hours to 10 days following a single pulse labelling. The proportion of DNA synthesizing basal and parabasal esophageal cells and of their daughter cells (as deduced by observations at various time intervals) was similar in animals harbouring neoplasias of the uterine cervix, in those treated with benzo(a)pyrene but having histologically normal cervical epithelium, in acetone treated as well as in untreated controls. Thus, in the model used herein, we failed to demonstrate increased cell proliferation in the esophageal mucosa of animals having a squamous cell neoplasia in the uterine cervix. The method appears, however, sensitive enough to register ongoing cell proliferation patterns and will be applied to the study of other experimentally induced tumors.