Do Oestrogens Regulate Placental Growth in the Mouse?

Publisher Website
Google Scholar
Abstract
Some effects of litter size, ovariectomy and estradiol (E2) on placental growth were determined. To increase variation in litter size, some mice had 1 oviduct removed and the remainder were unilaterally ovariectomized 3-4 wk prior to mating. After mating mice became unilaterally pregnant. Growth was examined qualitatively by measuring changes in placental DNA, protein, RNA:DNA ratios and in vivo incorporation of [5-3H]uridine into RNA. Spontaneous placental hyperplasia due to low litter size occurred to an equal extent in intact mice and mice which were ovariectomized on day 10 of pregnancy and given 1.0 mg progesterone (P) and 10 ng E2 daily. Ovariectomy on day 10 increased the incorporation of [5-3H]uridine into placental RNA on day 16 in mice with 6 or more fetuses. When mice were ovariectomized on day 5 and given 1.0 mg P and 10 or 60 ng E2 daily to maintain gestation, rates of placental growth remained similar to the rate in control, intact mice. Unlike the case in the rat, estrogens do not regulate placental growth in the mouse.