Classification of premalignant and malignant lesions developing in the rat mammary gland after injection of sexually immature rats with 1-methyl-1-nitrosourea

J Mammary Gland Biol Neoplasia. 2000 Apr;5(2):201-10. doi: 10.1023/a:1026495322596.


Premalignant and malignant stages of mammary carcinogenesis can be rapidly induced by injecting female rats i.p. with 1-methyl-1-nitrosourea (MNU)3 at 21 days of age. In this paper, the characteristics of this model are briefly reviewed and the histology of the lesions induced is presented and compared to those that occur in humans. Malignant mammary lesions induced in rats injected with MNU at 21 days of age are compared with the lesions that develop when MNU is administered to 50-day-old female rats.

MeSH terms

  • Adenocarcinoma / chemically induced
  • Adenocarcinoma / pathology
  • Animals
  • Carcinoma, Intraductal, Noninfiltrating / chemically induced
  • Carcinoma, Intraductal, Noninfiltrating / pathology
  • Female
  • Genes, ras
  • Hyperplasia
  • Lymphatic Metastasis
  • Mammary Glands, Animal / drug effects
  • Mammary Glands, Animal / pathology*
  • Mammary Neoplasms, Experimental / chemically induced
  • Mammary Neoplasms, Experimental / classification
  • Mammary Neoplasms, Experimental / pathology*
  • Methylnitrosourea*
  • Mutation
  • Neoplasm Metastasis
  • Precancerous Conditions / chemically induced
  • Precancerous Conditions / pathology*
  • Rats
  • Rats, Sprague-Dawley


  • Methylnitrosourea