Ide C
Arch Histol Jpn. 1983 Apr;46(2):243-57. doi: 10.1679/aohc.46.243.
Nerve segments approximately 6-7 mm long were excised from the predegenerated sciatic nerves of mice, and treated 5 times by repetitive freezing and thawing to kill the Schwann cells. Such treated nerve segments were grafted into the original place, being in contact with the proximal stump of the sciatic nerve. The animals were sacrificed 2, 3, 5, 7 and 10 days, 2, 3, 5 and 8 weeks after the grafting. The grafts were examined at the middle level, i.e., about 3-4 mm distal to the proximal end of the graft, by light and electron microscopy. Within 2-3 days after the grafting, the dead Schwann cells were disintegrated into fragments and gradually phagocytized by macrophages. However, the basal laminae of the Schwann cells remained as empty tubes (basal lamina scaffolds). The notable finding was that the regenerating axons always grew through these basal lamina scaffolds. New Schwann cells seemed to migrate along these axons from the proximal stumps. The number of axons growing through the basal lamina scaffolds gradually increased with time. These axons were surrounded in a bundle by Schwann cells. About 1 week after the grafting, axons began to be segregated into smaller bundles by Schwann cells. Axons with a relatively large diameter (about 2 microns) tended to be sorted out and surrounded by their own Schwann cells. The myelination began about 2 weeks after the grafting on such large diameter axons. The basal lamina scaffolds, through which the regenerating axons had grown, were gradually disintegrated into fragments by the expansive forces due to the increase in number and volume of the regenerating axons and Schwann cells. Groups of axons, which had been derived from the same basal lamina scaffolds, were enclosed with the cells resembling perineurial epithelial cells. These perineurial epithelial cells proliferated and further separated groups of axons into smaller ones or even into single axons. The number of myelinated axons increased with the advancement of regeneration. These results show that the basal lamina scaffolds of Schwann cells serve as efficient conduits for the elongation, maintenance and maturation of regenerating axons.
从小鼠预先变性的坐骨神经中切下约6 - 7毫米长的神经段，通过反复冻融处理5次以杀死施万细胞。将经如此处理的神经段移植回原位，使其与坐骨神经的近端残端接触。在移植后2、3、5、7和10天以及2、3、5和8周处死动物。通过光学显微镜和电子显微镜在移植神经段中间水平（即距移植近端约3 - 4毫米处）对移植组织进行检查。移植后2 - 3天内，死亡的施万细胞解体成碎片，并逐渐被巨噬细胞吞噬。然而，施万细胞的基膜仍保留为空管（基膜支架）。值得注意的发现是，再生轴突总是通过这些基膜支架生长。新的施万细胞似乎从近端残端沿着这些轴突迁移。通过基膜支架生长的轴突数量随时间逐渐增加。这些轴突被施万细胞成束包围。移植后约1周，轴突开始被施万细胞分隔成较小的束。直径相对较大（约2微米）的轴突倾向于被挑选出来并被其自身的施万细胞包围。髓鞘形成在移植后约2周开始于这些大直径轴突上。再生轴突生长通过的基膜支架，由于再生轴突和施万细胞数量及体积增加产生的膨胀力，逐渐解体成碎片。源自相同基膜支架的轴突群被类似于神经束膜上皮细胞的细胞包围。这些神经束膜上皮细胞增殖并进一步将轴突群分隔成更小的群甚至单个轴突。有髓轴突的数量随着再生进程而增加。这些结果表明，施万细胞的基膜支架作为再生轴突伸长、维持和成熟的有效管道发挥作用。
