[Tumor cells on the inside and tumor cells on the outside. A contribution to the diagnosis and elucidation of the pathogenesis of mammary tumors in dogs].

This review discusses some recent experience with intra- and extracellular components of tumours as markers for tumour diagnosis. Intermediate filaments are cytoskeletal proteins of either epithelial or mesenchymal cells. Antibodies raised against human intermediate filament proteins cross-react with their canine counterparts. A study of the presence and distribution of intermediate filaments in normal mamma and mammary tumours of dogs showed that they do not contribute to a more adequate classification of the tumours. However, the presence of vimentin in epithelial tumour cells may be a marker of malignancy. Proteoglycans are extracellular matrix proteins, containing long chains of glycosaminoglycans (GAGs). Analysis of the presence of GAGs in canine mammary tumours showed that accumulation of chondroitin sulfate, frequently of an abnormal type, was a predominant finding in all tumour types, but not in normal mamma, and was not related to biological behaviour. Although demonstration of the before-mentioned tumour components does not help tumour diagnosis, it may contribute to the elucidation of the development of such tumours as the complex and mixed adenomas of the mamma of which cartilage and bone are important constituents of unknown origin.