Intracellular collagen fibers in the capsule around silicone expanders in guinea pigs.

Ultrastructural studies of fibrous capsules surrounding silicone tissue expanders in guinea pigs revealed a number of fibroblasts containing collagen fibers inside cytoplasm with typical periodicity. These fibers were single or multiple, appeared straight, coiled, or bent, and lay in narrow, undulating membrane spaces. These intracellular collagen fibers were found in as many as 15% of the cells in capsules between 7 and 12 weeks of expansion. These observations suggest that during capsule development there is some imbalance between the synthesis of collagen fibers and their degradation. It is possible that increased synthesis of collagen fibers as well as their phagocytosis by fibroblasts may exist simultaneously.