Ultrastructural study of the differentiation of myoepithelial cells in the benign proloferative lesions of the breast

Ultrastructural features of myoepithelial cells in the benign proliferative lesion of the breast were studied. The meterials were 32 cases of fibroadenoma and 30 cases of adenosis. The emphasis was placed on the differentiation of myoepithelial cells, which has implied cell maturity. The most important indicator of the differentiation was the amount of myofilaments in myoepithelial cells. Well differentiated myoepithelial cell possessed well developed myofilaments, and vice versa. By the concept of myoepithlial differentiation. Myoepithelial cells were categorized into three different grades