REGIONAL DISTRIBUTION OF PROLIFERATING CELLS AND HORMONE RECEPTORS INTHE MAMMARY-GLAND OF SURGICALLY POSTMENOPAUSAL MACAQUES

Objective: To define the relative proliferative response and hormone r eceptors status in ten sites in the mammary gland of surgically postme nopausal cynomolgus macaques given hormone replacement therapy. Method s: Surgical postmenopausal cynomolgus macaques were given either no tr eatment (n = 4), conjugated equine estrogens (GEE, n = 4), or combined therapy with CEE and medroxyprogesterone acetate (n = 4). The drugs w ere administered in the diet, at doses equivalent on a caloric basis t o 0.625 mg/woman/day for CEE and 2.5 mg/woman/day for medroxyprogester one acetate. Immunostaining of mammary sections was done for estrogen receptor, progesterone receptor, and the proliferation marker Ki-67 MI B-1 (MIB). Comparisons were made between central and peripheral gland, by quadrant, left versus right, and with respect to distance from the nipple within each quadrant. Result: There were no significant differ ences in hormone receptor or MIB expression within different sites wit hin the gland. Conclusions: In the surgically postmenopausal, hormone- treated macaque, regional differences in estrogen and progesterone rec eptors and MIB staining are not apparent. The assumption of homogeneit y throughout the gland makes aspiration cytology and multiple biopsy s tudies feasible in this species.