Mast cells and eosinophils in rat mammary gland tumours induced by N-Nitroso-N-methylurea

The aim of the study was to evaluate the distribution and number of mast cells and eosinophils in rat mammary gland tumours induced by N-Nitroso-N-methylurea. The highest density of mast cells was found in cystic papillary adenocarcinomas of grade II. Eosinophils were detected only in the cystic papillary adenocarcinoma of grades I and II, in non-invasive cribriform adenocarcinoma and comedo-type carcinoma. Mast cell populations were observed perivascularly in the tumour stroma, in the host tumour interface, as well as in necrotic areas of neoplasms. Mast cells were observed to be intact according to their morphological changes, collectively referred to as degranulation. The obtained results indicate that mast cells and eosinophils play an important role in tumour micro-environment formation. The increased density of these cells in experimentally-induced rat mammary gland tumours suggests a poor prognosis in these cancers. Our results also confirmed that rat mammary gland tumours are good models for the study of breast cancers.