Effect of intravaginal application of prostaglandin E2 gel on the mechanical properties of the ovine cervix uteri at term.

The extensibility ("creep" or strain per minute) and the stretch modulus (stress per unit strain) of strips of cervical tissue were measured in vitro. Intravaginal application of prostaglandin E2 gel led to a fourfold increase in the extensibility (mean +/- SE, 15.45 +/- 0.26 versus 4.23 +/- 0.86 min-1; p less than 0.05) and a twofold reduction in the stretch modulus (mean +/- SE, 0.66 +/- 0.03 versus 1.28 +/- 0.12 N.mm2; p less than 0.0005). This marked increase in the degree of softening occurred in the absence of an increase in uterine activity or changes in plasma progesterone concentrations.