Mammogenesis in the ovariectomized mouse : a study of the effects of estradiol and progesterone : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Physiology at Massey University

Abstract

Immature ovariectomized female mice of the NOS albino strain were administered a series of estradiol treatments, and estradiol plus three different levels of progesterone, for 21 days in two separate experiments. Uterine weights, mammary gland areas, duct junctions/unit area, total duct junctions, mammary DNA and RNA were measured for all animals. Statistical analysis was carried out on all data. At estradiol doses between 0.00125-0.320 ug/day there was a steady increase in uterine weight, while mammary areas, unit junctions and total junctions increased to a peak at 0.020 and 0.040 ug/day estradiol respectively followed by an inhibition at higher levels. Changes in DNA and RNA did not follow this pattern but were more constant. At all progesterone doses an inhibition in uterine growth was seen when combined with 0.0050 ug/day estradiol, and a maximum was reached when the progesterone was combined with 0.010 ug/day estradiol, above which paint the curve remained flat showing an inhibition from growth observed with estradiol alone. The inhibition when 0.0050 ug/day estradiol was combined with progesterone was observed with all other parameters and also the inhibition at high levels of estradiol. However the final levels were higher than with estradiol alone. A third smaller experiment was carried out to show the time course of development of the mammary glands with 0.010 ug/estradiol and 0.010 ug/day estradiol plus 1 progesterone tablet. Mice were slaughtered at 3 day intervals during the 21 day treatment period. The results are discussed in relation to previous studies on mammary growth in ovariectomized mice and further areas of work suggested.