[Role of myoepithelial cells in the histogenesis of lobular breast cancer].

Myoepithelial cells (MC) and their distribution in lobular carcinoma (LC) of woman (4 cases) and dog (3 cases) mammary gland were studied by indirect Coons' method using monospecific antiserum against smooth muscle myosin. The following types of MC distribution in the duct-lobular system were distinguished: strictly peripheral localization and close connection with a basal membrane in LC in situ; disorderly distribution among tumour cells and complete disappearance from solid complexes of the infiltrating LC. It is shown that the alteration of normal architectonics of lobular structure is followed by MC move along the basal membrane resulting in the appearance of poorly differentiated MC. These facts do not allow one to draw the conclusion on the tumour nature of poorly differentiated MC; the decrease of their differentiation might depend upon the substrate.