[Cell proliferation during cicatrization of the integument in the 5 day chick embryo]

A cell proliferation study during wound healing of the excised integument of the flank in 5-day chick embryos was performed by pulse labelling using a single isotope (tritiated thymidine). The embryos were operated according to the experimental protocol already published (Thevenet and Sengel, 1973; Thevenet, 1981). 20 microCi of 3H-thymidine were deposited on the integument of the right flank of unoperated (controls) and operated embryos fixed 1 (start control), 2, 12 and 24 h after the excision. Mean labelling index of the unoperated epidermis was 13.7% at 5 days and 21.5% at 6 days of incubation. 2 hours after the excision, labelling index of the operated epidermis increased, on average, to 175% with respect to the labelling index of the controls, in the proximal zones near the wound edges; in the distal zones, the labelling index was lower than that of the controls. The labelling index in the dermis was, on average, 23.4% at 5 days and 28.5% at 6 days of incubation. 2 hours after the excision, the labelling index of the operated dermis increased, on average, to 165% with respect to that of the controls; later it decreased again and remained slightly higher or slightly lower than that of the controls. The increase of the labelling index of the operated integument persisted for a maximum of 6 h after the excision.