No abstract

No abstract

The antiuterotrophic efficacy of the pure antioestrogen ICI 182,780 has been demonstrated previously by magnetic resonance imaging (MRI) in ovariectomized oestrogen-treated monkeys (Macaca nemestrina). Further characterization of the effects of ICI 182,780 in intact adult female monkeys with normal menstrual cycles was undertaken to provide an indication of its potential actions in premenopausal women. Changes in the volume of uterine tissues were measured by MRI in early, mid and late cycle. The volume of the uterus varied up to fivefold between individual monkeys but serial observations in individuals provided sufficient precision to allow accurate assessments to be made of changes in the endometrium and myometrium during the course of the menstrual cycle and following ICI 182,780 administration. In comparison with its initial size in untreated monkeys, the endometrium increased in volume by 60% and 125% in the mid and late cycle respectively. In contrast, the size of the myometrium decreased significantly, by 16% from early to mid cycle and then recovered to near its initial volume in the late cycle. Treatment with ICI 182,780 beginning in the early part of the menstrual cycle prevented the growth of the uterus. The magnitude and duration of the response was dependent on whether or not ovulation occurred during treatment with ICI 182,780. In animals rendered anovulatory, growth of the endometrium was blocked completely by ICI 182,780 and the volume of the tissue declined below that present at the start of the menstrual cycle. Antiuterotrophic efficacy was significantly less in monkeys which ovulated during treatment with ICI 182,780.(ABSTRACT TRUNCATED AT 250 WORDS)

No abstract

Myometrial tissues from guinea pigs were quantitatively examined for gap junctions in electron micrographs. Small numbers of gap junctions were present between smooth muscle cells in myometria of pregnant guinea pigs at days 50 and 65 of gestation. The junctions increased in number and size at parturition on day 69 and decreased again to control levels 24 h after parturition. A similar increase in junctions occurred when abortion was induced by 16,16-dimethylprostaglandin E2 (PGE2) on day 65. There were no consistent or significant differences in number of gap junctions from myometrium taken over sites of placental attachment and from other sites. These results together with previous studies suggest that an increase in myometrial gap junction area is associated with and may be essential for parturition in guinea pigs, but the control of their development may differ from that in other mammals.