Inflammation and repair in the mammalian fetus: a reappraisal.

Review of our recent experimental findings and published studies indicates that the mammalian fetus responds to injury in a similar way to adult animals. Persistent inflammatory stimuli evoke an extensive cellular response whose composition varies with the stage of gestation and which is succeeded by formation of typical scar tissue. In fetal sheep excisional skin wounds and wounds in bone, muscle, tendon, and nerve heal by scar. There is disagreement whether, early in gestation, sutured incised skin wounds heal without scar, but this cannot justify a claim of scarless fetal healing. In the immature fetuses of rats and rabbits sutured wounds heal rapidly but open wounds remain unhealed until birth. Injury to deeper tissues has not been examined. The little evidence available suggests that inflammation and repair in the human fetus is similar to that in fetal sheep.