Effects of neonatally-administered 17beta-estradiol on induction of mammary carcinomas by 7, 12-dimethylbenz[a]anthracene in female rats.

Various doses of 17beta-estradiol (E2) were administered subcutaneously to inbred female Sprague-Dawley (SD) rats once at birth. At 50 days after birth, rats in all the groups were given 10 mg of 7, 12-dimethylbenz[a]anthracene (DMBA). In the 1000 microg group, the incidence and number of mammary carcinomas were markedly low, while in the 10 microg group, a large number of mammary carcinomas was noted.

Malignant myoepithelioma with a squamous epithelial component in the mammary gland of a cynomolgus monkey.

A solid mass arising from the mammary gland was found in a 7-year-old female cynomolgus monkey. Histologically, the mass consisted of 2 components: spindle-shaped or ovoid sarcomatous cells and squamous epithelial cells. Metastatic nodules noted in the lung, liver and the gallbladder had the same histological features as the mammary mass.