The effect of pulsed expansion of subfascially placed expanders on the extent and duration of mitosis in the capsule and rat integument

This study investigated the mitotic activity in the subdermally induced capsule and the epithelium surrounding tissue expanders maintained by pulsed expansions. Tissue expanders were placed into the fascial plane beneath the panniculus muscle of the rat and expanded sequentially. The volume in the expander was rapidly increased to a constant level and maintained for 48 hours; this was followed by a total decrease of volume for 48 hours. The procedure was repeated with volumes of 20, 30, and 40 mL. At the conclusion of each cycle of expander inflation, a group of rats was killed, and biopsy specimens of the induced capsule and epithelium were obtained. The developing capsule exhibited a significant increase in the mitotic index in the layers adjacent to the expander. The highest mitotic index was obtained with an inflation of 30 mL. These observations suggest that cellular proliferation, growth, and development of the extracellular matrix in the induced subdermal capsule can be sustained by pulsed volume changes in the expander.