Gilmore S A, Sims T J
Department of Anatomy, University of Arkansas for Medical Sciences, Little Rock 72205.
J Chem Neuroanat. 1993 Jul-Aug;6(4):191-9. doi: 10.1016/0891-0618(93)90041-2.
Patterns of Schwann cell myelination of long-projecting axons in the spinal cord were studied. The goal was to determine if such axons arising from neurons whose somata and processes are normally confined to the central nervous system can interact effectively with Schwann cells, the myelinating cells of the peripheral nervous system. In one paradigm Schwann cells develop in the dorsal funiculi of the lumbar spinal cord subsequent to radiation-induced alterations in development of the glial populations. Light and electron microscopic evaluations were made in the region of the corticospinal tracts (CSTs), which in the rat occupy the base of the dorsal funiculi. At 90 days following irradiation, larger axons of these tracts (> 1.5 microns in diameter) were myelinated by Schwann cells, and smaller axons were ensheathed by them. In the second paradigm cultured Schwann cells were injected into the medial portions of the ventral funiculi at 13 days post-irradiation when the glial population was markedly reduced. Earlier investigations from this laboratory demonstrated that Schwann cells do not develop in the irradiated ventral funiculi, as they do dorsally. When placed in proximity to long-projecting axons in the medial portion of the ventral funiculi, the Schwann cells either formed compact myelin sheaths or ensheathed axons, depending upon their diameter. Fasciculation and presence of collagen were characteristic of this paradigm but were absent from the Schwann cell-occupied regions of the CSTs. This probably relates to the presence of fibroblasts in the injected cultures.(ABSTRACT TRUNCATED AT 250 WORDS)
研究了脊髓中长投射轴突的施万细胞髓鞘形成模式。目的是确定源自其胞体和突起通常局限于中枢神经系统的神经元的此类轴突是否能与外周神经系统的髓鞘形成细胞施万细胞有效相互作用。在一种模式中，在辐射诱导神经胶质细胞群体发育改变后，施万细胞在腰脊髓的背侧索中发育。对皮质脊髓束（CSTs）区域进行了光镜和电镜评估，在大鼠中，皮质脊髓束占据背侧索的基部。照射后90天，这些束的较大轴突（直径>1.5微米）被施万细胞髓鞘化，较小轴突被其包裹。在第二种模式中，在照射后13天，当神经胶质细胞群体明显减少时，将培养的施万细胞注入腹侧索的内侧部分。该实验室早期的研究表明，施万细胞不像在背侧那样在受照射的腹侧索中发育。当置于腹侧索内侧部分的长投射轴突附近时，施万细胞根据轴突直径形成紧密的髓鞘或包裹轴突。束状结构和胶原的存在是这种模式的特征，但在CSTs的施万细胞占据区域中不存在。这可能与注射培养物中存在成纤维细胞有关。（摘要截短于250字）
