RESUMO
To observe the cellular expression of extracellular matrix components during mouse skin regeneration, the wounded skin samples were processed by immunoelectronmicroscopic methods, using primary antibodies for fibronectin, collagen type IV and laminin. The tissues were observed under transmission electron-microscope. The results were summarized as follows. 1. The granulation tissues and x-cells were observed in the wound margin at 18 hr post injury. The number of fibroblasts was increased in the granulation tissues at 1 day post injury. 2. The expression of fibronectin was observed in x-cells at 18 hr post injury, and in fibroblasts at 1 day post injury. In x-cells, after 1 day post injury, the expression of fibronectin was decreased. 3. At 1 day post injury, the expression of collagen type IV was increased in fibroblasts whereas not in x-cells. 4. The expression of laminin was increased by 18 hr post injury, but decreased after 1 day post injury. On the basis of above findings, in mouse, the regenerations of wounded skin were faster than other animals. The first step, infiltration response, was processed till 18 hr or 1 day post injury. The second step, fibroblast proliferation phase, began at 1 day post injury. In the regenerations of wounded skin, x-cells migrated to the wound region and activated, earlier than fibroblast. Thereafter, x-cells which appeared to be transformed into fibroblasts, played an important role in the synthesis of fibronectin and collagen type IV, and the formation of granulation tissue, with migrated fibroblasts to the wound region.