After transection the lumbar spinal cord of lizards forms a bridge of connective and nervous tissues between the severed proximal and distal ends of the cord. The types of proliferating cells activated in the injured spinal cord have been analyzed using light and ultrastructural immunolabeling for 5BrdU and nestin from 11 to 34 days after injury, when recovery of some hindlimb movements has occurred. At 11–22 days post‐transection an intense proliferation of glial, immune and meningeal cells takes place. Nestin is almost absent in the normal spinal cord but becomes detectable at 11–34 days postinjury in ependymal and sparse glial cells located in the bridge region. At 11–22 days postinjury also numerous macrophages, lymphocytes, and some plasma cells appear proliferating during the intense inflammatory and antimicrobial phase. Phagocytosis within the injured spinal cord probably decreases inflammation and may indirectly promote axonal regeneration. Proliferating cells likely derive from precursor or stem elements of the reactive ependymal epithelium, but also from glial cells and meningeal fibroblasts. This is indicated by the presence of 5BrdU‐long retaining labeling cells of glial and fibroblast types located in the stumps of the spinal cord and in the bridge. The present observations suggest that meningeal, ependymal, and numerous glial cells are the precursors of those forming the bridge region. Among glial cells, sparse oligodendrocytes myelinating the few axons present at 34 day after the injury also appear capable to proliferate. The myelinated axons are probably involved in the limited but important functional recovery of limb movements observed after 30–90 days postinjury.

中文翻译：

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对蜥蜴恢复腰脊髓的观察表明，形成桥区的细胞有多个来源，包括免疫细胞

蜥蜴的腰椎脊髓在横断后在脊髓的切断近端和远端之间形成结缔组织和神经组织的桥梁。在受伤后 11 至 34 天，当一些后肢运动恢复时，使用光和超微结构免疫标记对 5BrdU 和巢蛋白进行了分析，分析了在受伤脊髓中激活的增殖细胞类型。在横断后 11-22 天，胶质细胞、免疫细胞和脑膜细胞发生强烈增殖。巢蛋白在正常脊髓中几乎不存在，但在损伤后 11-34 天可在位于桥区域的室管膜和稀疏神经胶质细胞中检测到。在损伤后 11-22 天，大量巨噬细胞、淋巴细胞和一些浆细胞在强烈的炎症和抗菌阶段出现增殖。受损脊髓内的吞噬作用可能会减少炎症并可能间接促进轴突再生。增殖细胞可能来自反应性室管膜上皮的前体或干细胞，但也可能来自神经胶质细胞和脑膜成纤维细胞。这通过位于脊髓残端和桥中的神经胶质和成纤维细胞类型的 5BrdU 长保留标记细胞的存在来表明。目前的观察表明，脑膜、室管膜和许多神经胶质细胞是形成桥区域的细胞的前体。在神经胶质细胞中，在损伤后 34 天形成少数轴突髓鞘的稀疏少突胶质细胞似乎也能够增殖。