The effects of partial and total amniotic fluid exclusion on excisional fetal rabbit wounds

Previous studies have consistently demonstrated that fetal rabbit excisional wounds exposed to amniotic fluid do not heal in utero. This study examines fetal wounds covered to exclude amniotic fluid. Full-thickness excisional wounds were created on fetal rabbits on day 25 of gestation. The following three treatment groups were examined: uncovered (n = 19 live); covered, a silicone cover was sutured over the wound (n = 14 live); and donut, a silicone cover containing a 2-mm central hole was sutured over the wound (n = 6 live). Fetuses were returned to the uterus and harvested by cesarean section 72 hr postoperatively. Fetal (covered) wounds excluded from amniotic fluid contracted and reepithelialized up to confluence. Sixteen of 19 uncovered wounds expanded, 3 were unchanged; minimal reepithelialization was present in all wounds. Partially (donut) covered wounds exhibited an intermediate response. This study shows that excisional wounds in the rabbit fetus respond to injury by contracting and reepithelializing when excluded from amniotic fluid.