OBJECTIVEThe study was to evaluate the microscopic changes on skin and soft tissue after repeated expansion for clinical work.

METHODSSix little pigs were divideded as: conventional expansion group, repeated expansion group, and blank control group. Histologic, ultrastructure and bFGF of the skin were observed and measured in each group after samples had been made.

RESULTSThe skin and soft tissue after repeated expansion were healthy on the whole. Compared with the conventional expansion group, there was more microscopic change in the repeated expansion group. Collagen fibers were injured evidently. Cells were injured slightly and proliferated much more, and moreover, they were more activated. The content of bFGF was more higher.

CONCLUSIONSThe skin and soft tissue after repeated expansion are healthy on the whole by more growth and more repair though repeated expansion may result in more injuries. So repeated expansion is safe and feasible.