Chi N H, Dahl D
Exp Neurol. 1983 Jan;79(1):245-64. doi: 10.1016/0014-4886(83)90394-1.
Autologous sciatic nerve was grafted into rat brain by (i) passing an 8-mm segment of nerve tied to a straight surgical needle through two craniotomy holes ("through-and-through" model); (ii) inserting a small tube of polyethylene containing the 8-mm nerve piece ("nerve-within-tube" model). Longitudinally oriented neurofilament-positive fibers were consistently observed within the graft. Compared with the through-and-through model, axonal sprouting in the nerve-within-tube model followed a slow-motion pattern so that a growing front of regenerating axons could be easily identified and more easily related to the cellular events occurring in Wallerian degeneration. In the through-and-through model, regenerated axons at the brain-nerve interface followed a disorganized, tortuous course so that direct continuity between brain and graft was difficult to demonstrate. The reverse was true in the nerve-within-tube model, i.e., axons penetrated directly into the graft. The difference in orientation of axonal growth at the brain-graft interface appeared to be related to the glial reaction. In the through-and-through model, reactive astrocytes formed a mesh of randomly oriented fibers in the damaged brain tissue facing the graft (anisomorphic gliosis). Conversely, longitudinally oriented fibers extended directly from the brain to the graft in the nerve-within-tube model, where brain damage was substantially reduced (isomorphic gliosis). A different type of glial fibrillary acidic (GFA) protein-positive fibrous structures was identified in the graft. Compared with reactive astrocytes, these structures were more elongated, more uniform in diameter, and less brightly immunofluorescent. Moreover, they were present throughout the graft, whereas astrocytes were confined to the distal end of the transplant, i.e., the part of nerve close to the brain-graft interface. Based on previous reports in the literature we interpret these GFA protein-positive structures as reacting Schwann cells.
将自体坐骨神经移植到大鼠脑内，方法如下：(i) 将一段8毫米长的神经系在一根直的手术针上，穿过两个颅骨切开孔（“贯穿”模型）；(ii) 将包含8毫米神经段的一小段聚乙烯管插入（“管内神经”模型）。在移植物内始终能观察到纵向排列的神经丝阳性纤维。与“贯穿”模型相比，“管内神经”模型中的轴突发芽呈慢动作模式，因此再生轴突的生长前沿很容易识别，并且更容易与沃勒变性中发生的细胞事件相关联。在“贯穿”模型中，脑-神经界面处的再生轴突走行紊乱、曲折，因此难以证明脑与移植物之间的直接连续性。“管内神经”模型则相反，即轴突直接穿透移植物。脑-移植物界面处轴突生长方向的差异似乎与胶质反应有关。在“贯穿”模型中，反应性星形胶质细胞在面对移植物的受损脑组织中形成了随机排列的纤维网（异形性胶质增生）。相反，在“管内神经”模型中，纵向排列的纤维直接从脑延伸到移植物，其中脑损伤明显减轻（同形性胶质增生）。在移植物中发现了一种不同类型的胶质纤维酸性蛋白（GFA）阳性纤维结构。与反应性星形胶质细胞相比，这些结构更长、直径更均匀，免疫荧光亮度更低。此外，它们遍布整个移植物，而星形胶质细胞局限于移植物的远端，即靠近脑-移植物界面的神经部分。根据文献中的先前报道，我们将这些GFA蛋白阳性结构解释为反应性雪旺细胞。
