Immunohistochemical examination of neural cell adhesion molecule (NCAM), tenascin and fibronectin on the development of cartilaginous tissue in canine mammary mixed tumors.

The expression of neural cell adhesion molecule (NCAM), tenascin and fibronectin during cartilage-like tissue formation in canine mammary mixed tumor was immunohistochemically examined. Mirror-image serial sections revealed that proliferating myoepithelial cells simultaneously expressed these adhesion molecules where no cartilage-like tissue and no expression of cartilage-specific type II collagen were observed. With the formation of cartilaginous tissue, positive signals of these adhesion molecules decreased in chondroblast-like cells, the cartilaginous tissue was hyalinized and mature chondrocyte-like cells no longer expressed these cell adhesion molecules. NCAM, tenascin and fibronectin, therefore, may play crucial roles on the proliferation of myoepithelial cells and the subsequent development of cartilaginous tissue in canine mammary mixed tumor.