SPONTANEOUS MOUSE MAMMARY-TUMORS - INCIDENCE AND CYTOKERATIN EXPRESSION

The purpose of this study was to advance our knowledge of the histogen esis of spontaneous mammary tumours in laboratory mice. Normal mammary tissue and 19 spontaneous mammary tumours from adult female mice were examined using monoclonal and polyclonal antibodies differing in thei r recognition of various cytokeratin intermediate filament proteins (C Ks). All neoplasms were intraductal and were invasive carcinomas with a tubular, papillary, cystic or solid growth pattern. CK8-positive rea ctions were detected in the normal alveolar and ductal epithelia and C K5- and CK14-positive reactions were seen in myoepithelial cells of no nlactating mammary glands. Positive staining for CK5 and CK8 was detec ted in all rumours and CK14 was expressed in those with a papillary pa ttern. Comparisons between non-lactating glands and tumours indicated that the neoplasms were well or moderately differentiated, there was n o squamoid differentiation and that they arose from the alveoli and du ct system, not the myoepithelial cells.