[Modeling of differentiation and physiological involution in the tissues of induced cancer of the mammary gland].

The experiments used rats with mammary tumors induced by intravenous injection of DMBA. The animals were treated with alternating courses of estrogen and anti-estrogen (tamoxifen). The former was given in combination with papaverin and low doses of vitamin A. This was followed by light and electron microscopic examination of breast tumors which revealed activation of cell differentiation and tissue-specific function. The death of cells (active autolysis) was similar to one taking place in the course of physiologic involution of the organ but it was unlike liquefying and coagulation necrotic processes usually occurring in tumor.