| Aims:1. To develop a procedure by which Schwann cell and myelin in the peripheral nerve could be removed while the basal lamina tubes remained intact ,and to obtain a long acellular nerve scaffold.2. To observe the short-term nerve regeneration on rat models with facial nerve defects bridged by acellular nerve allograft made through chemical extraction.3. To detect the variation of Schwann cell following facial nerve defects bridged by acellular nerve allograft in rats.4. To explore the possibility to bridge facial nerve defects by acellular xenogeneic nerve made through chemical extraction .Methods:1. Ten rat tibial nerve and ten rabbit peroneal nerve 20mm long were excised and cleaned from external debris respectively. The nerve were treated with a solution of Triton X-100 and deoxycholate at room temperature .After a final wash in water , the nerves were stored in phosphate-buffered saline( PBS,pH7.4) at 4C. HE staining, Luxol fast blue (LFB) staining and alkaline phosphatase staining and the immunocytochemical staining for the presence of SlOO were performed to visualize cells and myelin respectively; and the immunocytochemical staining for the presenceof laminin were performed to visualize the presence of laminin, a Schwann cell lamina component, both in fresh and acellular nerve segments.2. 60 rats were divided into three groups: (A) fresh tibial nerve autograft ,20 cases;(B) chemical extracted tibial nerve allograft, 20cases; (C) fresh tibial nerve allograft, 20 cases. The model of mandibular division (6mm in length ) of rat unilateral facial nerve was set up. The defects were bridged by the above mentioned three kinds of nerve grafts respectively. Efficacy of nerve and muscle and nerve regeneration were observed by using electromyography, horseradish peroxidase(HRP) retrograde trace, HE staining, LFB staining , the immunocytochemical staining, methylene blue staining and transmission electron microscope respectively at 5 postoperative month.3. 50 rats were divided into five groups: D, E, F, G, H for different periods(l week, lOdays, 2 weeks, 4 weeks.and 8 weeks)after the operation of the facial defects bridged by chemical extracted tibial nerve allograft in rats. The immunocytochemical staining for the presence of S100 was performed to visualize the Schwann cell.4. 120 rats were divided into six groups: (I) fresh nerve autograft, 20 cases;( J) fresh xenogeneic acellular nerve graft ,20cases; (K) xenogeneic acellular nerve graft predegenerated for 1 week, 20cases; (L) xenogeneic acellular nerve graft pre-degenerated for 2 weeks,20cases; (M) xenogeneic acellular nerve graft predegenerated for 3 weeks,20cases; (N) fresh xenogeneic nerve graft, 20 cases. The model of mandibular division (6mm in length ) of rat unilateral facial nerve was set up. The defects were bridged by the above mentioned six kinds of nerve grafts respectively. Efficacy of nerve and muscle and nerve regeneration were observed by using electromyography, HRP retrograde trace, methylene blue staining and transmission electron microscope respectively at 5 postoperative month.Results:1. The acellular rat tibial nerve and acellular rabbit peroneal nerve were white long cylinder with well elasticity and ductility. HE , LFB , alkaline phosphatase staining and the immunocytochemical staining for the presence of S100 revealed that cells, axons and myelin sheath were removed and basal membrane was preserved afterextraction procedure. The immunocytochemical staining for the presence of laminin showed that the Schwann cell basal lamina component were present in the nerves after chemical extraction.2. The number of regenerative myelinated axons, diameter of myelinated fibers and thickness of myeiin sheath in group B was satisfactory when compared with that in group A. Regenerated microfascicles distributed at the center of grafting part, and a multitude of myelinated nerve fibers occurred at the distal part in group B. The regenerated nerve fibers had normal morphological and structural char...
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