Contraction of the capsule around silicone implant causes deformity for firmness of the prosthesis. As to the cause of capsular contraction, contractility of myofibroblasts or phisicochemical reorganization is suggested. In order to investigate the causative factor, silicone elastomer was inserted below the panniculus muscle of rats and consequent capsular tissue around the silicone implant was examined light and electron microscopically, 3 days and 1, 2, 3, 4, 8, 16 and 20 weeks after the insertion.
Three days after the insertion, mild inflammatory reaction was noted in the surrounding tissue and after 1 week, a fibrous capsule was formed, which appeared more collagenous as time lapsed. During the period of capsule formation, fibroblasts had rich rough endoplasmic reticulum and prominent Golgi apparatus indicating active synthesisof collagen precursors. After 2 weeks, the number of the fibroblasts decreased progressively and arranged in parallel one another; collagen fibers in the intercellular matrix increased in amount and appeared more compact and regular. Some of the fibroblasts were found to have filaments with indistinct dense bodies, and a few ’classic’ myofibroblastis were noted at later stage.
From these results, it is suggested that progressive increase in amount and structural organization of collagen fibers, as well as contractility of myofibroblasts, may play a role in capsular contraction by silicone implantation.
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