Chronological observation of mouse endometrial carcinogenesis induced by N-methyl-N-nitrosourea and 17 beta-estradiol.

Chronological observation of the neoplastic endometrial lesions induced by N-methyl-N-nitrosourea (MNU) and 17 beta-estradiol (E2) were studied. E2 induced cystic glandular hyperplasia, but adenomatous hyperplasia was induced predominantly by MNU. Atypical hyperplasia and adenocarcinoma were induced cooperatively by E2 and MNU, and first found at week 12; the incidence of adenocarcinoma increased in accordance with the week-course. Some atypical hyperplasia might be changed to adenocarcinoma. Mean AgNORs numbers in (pre)neoplastic lesions increased in accordance with neoplastic changes. This model was useful for clarifying histogenesis of human endometrial carcinogenesis.