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The effect of age on the histopathogenesis of 7,12‐dimethylbenz(a)‐anthracene‐induced mammary tumors in the lewis rat
Author(s) -
Haslam Sandra Z.
Publication year - 1980
Publication title -
international journal of cancer
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.475
H-Index - 234
eISSN - 1097-0215
pISSN - 0020-7136
DOI - 10.1002/ijc.2910260315
Subject(s) - dmba , hyperplasia , pathology , mammary tumor , mammary gland , carcinogen , 7,12 dimethylbenz[a]anthracene , stage (stratigraphy) , medicine , biology , cancer , carcinogenesis , breast cancer , paleontology , genetics
The influence of age at time of DMBA administration on (l) the histopathogenesis and site of mammary tumor origin and (2) the precancerous nature of DMBA‐induced mammary dysplasias was examined in Lewis rats between 25 and 200 days of age. Rats were killed at various times after carcinogen treatment and the numbers of tumors and dysplasias were recorded from microscopic examination of mammary gland wholemounts. We found that, in all age‐groups tested, mammary tumors always appeared to originate within mammary end‐buds and terminal ductules and that terminal due‐tule hyperplasia appeared to be an early stage in tumor formation. Age‐related differences in susceptibility to tumor development were paralleled by similar differences in susceptibility to the development of terminal ductule hyperplasias. In contrast, although age‐related differences in susceptibility to the development of hyperplastic alveolar nodules were also noted, they did not correspond to those observed for tumor development. Thus, hyperplastic alveolar nodules did not appear to be a site of tumor origin in situ or directly related to tumor development.