大鼠坐骨神经再生过程中的施万细胞自噬作用

目的 探讨大鼠坐骨神经再生过程中的细胞自噬作用。方法 横切大鼠坐骨神经制作wallerian变性模型．分别于造模后0、0．5、1．0、1．5、2．0、3．0、4、5、7、10、15d取远断端组织行电镜结构观察。结果 轴突在第0．5天时从髓鞘脱离，溃变呈空泡状。第2天开始髓鞘皱褶、断裂形成碎片，神经膜细胞(Schwann cell，施万细胞)内见大的膜结合髓鞘碎片和许多散在小碎片，并与溶酶体融合形成自噬泡，呈酸性磷酸酶(AcPase)阳性。第4天时内膜区偶见幼稚细胞，1周后见大量幼稚细胞。第7天后施万细胞内自噬泡数量开始减少。实验全程偶见巨噬细胞，内有吞噬泡。结论大鼠坐骨神经再生过程中溃变髓鞘主要经施万细胞自噬清除。施万细胞脱分化为施万细胞祖细胞后大量增殖分化参与神经再生过程。

Autophagic effect of Schwann cells in the regeneration of rat sciatic nerves]

OBJECTIVE: To investigate the autophagic effect of Schwann cells in the process of rat sciatic nerve regeneration. METHODS: Wallerian degeneration model was established by transecting the rat sciatic nerve. Samples from the distal stump were obtained 0, 0.5, 1, 1.5, 2, 3, 4, 5, 7, 10, and 15 days respectively after the transaction, and ultrathin sections were prepared for examination with electron microscope. RESULTS: Axons started to separate from the myelin sheath at day 0.5 after the transection, followed by rapid vacuolar degeneration. Since day 2, the myelin sheath folded and broke into fragments, and in the Schwann cells large cell membrane-bound myelin debris and many scattered small fragments could be seen to fuse with the lysosomes to form ACPase reaction-positive autophagic vacuoles. Immature cells were occasionally seen in the endoneural space, appearing in large amount a week later. After day 7, the number of autophagic vacuoles began to diminish. In the entire course of the observation, macrophages containing autophagic vacuoles, were spotted only occasionally. CONCLUSION: The degenerated myelin debris are cleared mainly through the mechanism of autophagy by the Schwann cells during regeneration of rat sciatic nerve. Schwann cells dedifferentiate into Schwann cell precursors, which then proliferate and differentiate to take part in the regeneration of the nerves.