Cervical softening in late pregnant sheep by infusion of prostaglandin E-2 into a cervical artery.

Cervical softening was induced in late pregnant sheep by infusion of PGE-2 into a cervical artery. The effect of this treatment was assessed by measurement of the extensibility in vitro of a strip of cervical tissue. After infusion of a saline/ethanol mixture extensibility was 2.84 X 10(-3) +/- 0.3 X 10(-3) min-1 (mean +/- s.e.m., N = 5); after infusion of PGE-2 it increased significantly (P less than 0.02) to 8.6 X 10(-3) +/- 1.8 X 10(-3) min-1 (N = 6). Infusion of PGE-2 did not increase uterine activity, and there was no significant change in the concentration of progesterone in the maternal jugular venous plasma. These data suggest that PGE-2 might act as a mediator of cervical softening in vivo and show that the cervix can soften in the absence of uterine contractions.