Scanning electron microscopy of wound healing in rat embryos

Wound healing in rat early embryos has been studied by scanning electron microscopy. Initially the wound gapes slightly and cells peripheral to the wound assume a cobble-stone appearance. Wound closure is quite rapid; some small wounds are almost closed within 10 min of incision. Wound closure is accompanied by the appearance of some elongated cells at the wound edge. These features are similar to, although less pronounced than, those which have been observed to accompany wound closure in amphibian and avian embryos. Healing of wounds made in the amnion is also accompanied by changes in the shapes of cells at the wound margins. Wound healing in embryos cultured in Hank's saline is similar to wound healing in embryos cultured in serum, suggesting that the macromolecular components of serum are not essential to wound healing. Cytochalasin B, which inhibits wound closure in amphibian embryos, does not inhibit wound healing in rat early embryos unless used at a concentration high enough to cause cell dissociation. Similarly chelation of the free calcium in the medium, which also prevents wound closure in amphibian embryos, does not inhibit wound closure unless the embryo is dissociating. Removal of free calcium does however cause collapse of the elevated neural folds. These observations suggest that the cellular mechanisms involved in wound healing are different in mammalian and amphibian embryos.