OBJECTIVETo observe the ultrastrual changes of the skin between the continuous tissue expansion and the conventional tissue expansion.

METHODSTwelve white piglets were used for this study on an animal model of tissue expansion with the continuous tissue expansion group and the conventional tissue expansion group. The tissue samples in each group were harvested and prepared for the transmission electron microscope observation.

RESULTSThe interspace among basal cells and spinose cells was increasing and the numbers of cell conjunctures were decreasing in the both groups. However, these changes in the continuous tissue expansion group were more obvious than in the conventional tissue expansion group. In the dermal layer of the skin, the ultrastructure of collagen fibers were basically normal. But, the fibroblasts and capillary endothelia cells were more activated in the continuous tissue expansion group, compared with the conventional tissue expansion group. The fibroblast apoptosis and collagenolysis spots were observed in both of the groups, while the red blood cells were also found in the tissue leaked outsides from the blood vascular cavities.

CONCLUSIONTissue expansion may result in tissue growth and tissue degeneration in the same time.