The effect of an intrauterine device on uterine weight and water content and on genital tract glycogen of cycling, ovariectomized, pseudopregnant or oestrogen-treated hamsters.

In order to investigate the mechanisms of the intrauterine devices antifertility effect the quantitative effect of an IUD on the weight and water content of the genital tract during the preovulatory phase of the cycle after uterine trauma and following castration with and without administration of estrogen was studied in 42 hamsters. 12 animals were observed for characteristic vaginal cycle changes after 3 cycles with the IUD in situ. 10 hamsters were mated with vasectomized males and examined by laparotomy on Day 4 of pseudopregnancy. 20 hamsters were oophorectomized at the time of IUD insertion and examined 7 days later. Half of these animals were administered 10 mcg of estrogen im 24 hours before autopsy. The presence of the unilateral IUD resulted in uterotrophic effects in the intact pseudopregnant and ovariectomized hamsters with or without the estrogen administration. In the pseudopregnant hamsters the glycogen content was significantly reduced in the IUD-treated uterine horn (p less than .01). Estrogen administration increased glycogen synthesis but the IUD did not. No difference in uterine water content was found in the presence of the IUD.