The chick embryo chorioallantoic membrane as an in vivo wound healing model

The chick embryo chorioallantoic membrane (CAM) was used as an in vivo wound healing model. A full excision of a 1 mm2 CAM area was filled by a granulation tissue after 96-120 h, which eventually formed a scar in 75% of the cases. In the remaining 25%, a solution of continuity was left which, however, was smaller in size than the one observed immediately after the excision. Under the microscope, the CAM area involved in the repair process showed: i. hyperplasia of the chorionic epithelium; ii. about three times as many microvessels and fibroblasts in the mesenchyme as in the normal adjacent control regions; iii. an inflammatory infiltrate mostly consisting of macrophages; and iv. a strong positivity for fibronectin in the extracellular matrix. The validity of this experimental model appears to be confirmed by the fact that we were able to reproduce all the critical events controlling the wound healing process, such as re-epithelization, angiogenesis, formation of an inflammatory infiltrate and deposition of one of the main constituents of the extracellular matrix, such as fibronectin.