Smith G V, Stevenson J A
Department of Anatomy, Medical College of Virginia, Virginia Commonwealth University, Richmond 23298.
Exp Brain Res. 1988;69(2):299-306. doi: 10.1007/BF00247575.
Peripheral nerve grafts were implanted bilaterally into the diencephalon of adult hamsters. One graft segment contained both viable Schwann cells and their basal lamina tubes. The Schwann cell population in the second graft segment was killed by freezing prior to implantation. Seven weeks after graft implantations, the extracranial end of each graft segment was exposed, transected and labelled with a fluorescent tracer substance. One week after the labelling procedure each animal was perfused and the diencephalon and midbrain were examined. Ultrastructural analyses of both types of graft demonstrated the persistence of the Schwann cell-derived basal lamina tubes. Retrogradely labelled neurons were found in all cases in which an intact graft remained in place for two months, but were seen in only one case with a frozen graft. Large numbers of myelinated and unmyelinated axons were seen within the intact grafts, but no axons were found in the previously frozen grafts. These results indicate that lesioned CNS axons are able to regenerate vigorously when provided with an environment which includes viable Schwann cells. But, CNS axons regenerate less well, if at all, when Schwann cells are absent. Further, it appears that Schwann cell-derived basal lamina tubes, when isolated from their parent cells, are insufficient to initiate or sustain CNS axonal regeneration.
将周围神经移植物双侧植入成年仓鼠的间脑。一个移植物片段包含存活的雪旺细胞及其基膜管。第二个移植物片段中的雪旺细胞群体在植入前通过冷冻杀死。移植后7周，暴露每个移植物片段的颅外端，横断并用荧光示踪剂标记。标记程序1周后，对每只动物进行灌注，并检查间脑和中脑。对两种类型移植物的超微结构分析表明，雪旺细胞衍生的基膜管持续存在。在所有完整移植物放置两个月的病例中均发现逆行标记的神经元，但在冷冻移植物的病例中仅在1例中见到。在完整的移植物中可见大量有髓和无髓轴突，但在先前冷冻的移植物中未发现轴突。这些结果表明，当提供包括存活雪旺细胞的环境时，受损的中枢神经系统轴突能够有力地再生。但是，如果没有雪旺细胞，中枢神经系统轴突再生得较差，甚至根本不再生。此外，似乎从其母细胞分离出来的雪旺细胞衍生的基膜管不足以启动或维持中枢神经系统轴突再生。
