Active epidermal movement in human skin in vitro

Epidermal cells migrate from the edges of adult human skin in culture during the first 48 h. In order to determine whether mitotic acitivity was responsible for this cell movement the autoradiographic labelling index for cells in DNA synthesis was determined for skin at different stages of culture. The labelling index of skin maintained for 48 h but labelled with tritiated thymidine in the first 4 h, did not differ significantly from skin both maintained and labelled for 4 h only. Skin maintained for 48 h but labelled in the last 4 h showed a much lower labelling index. No normal mitotic figures were seen in the epidermis of skin maintained for 48 h but exposed to colcemid for the last 4 h of culture. It has been concluded that at least in short-term organ culture of adult human skin there is a phase of mitotic arrest and that epidermal migration during the first 48 h is an active process independent of mitotic activity.