Wound healing in chick embryos in vivo and in vitro

Abstract

The faculty of chick embryos for healing skin and corneal wounds varies significantly with age. After lesions in vivo, proliferation of epithelial cells proceeds, but migration over the wound is absent until at least the tenth day of incubation, at which date it automatically starts regardless of how much time has elapsed since the injury. This rules out any of the immediate traumatic effects of wounding as being causally related to migration. When cultivated on a plasma clot in vitro, however, both skin and cornea fragments are capable of migratory wound healing at all ages. This proves that the early failure in vivo is not due to intrinsic immobility of the epithelial cells; nor could it be definitely connected with cell-to-substratum relations. Tentatively, one could consider the critical change to occur in the humoral milieu, as the hormone system becomes active about that time. The remarkable property of dissociating growth and proliferation from migratory activity, exhibited during the first half of the developmental period, makes the chick embryo uniquely suitable for more penetrating analysis of the relative independence of the components of wound healing.