Bunge M B, Williams A K, Wood P M, Uitto J, Jeffrey J J
J Cell Biol. 1980 Jan;84(1):184-202. doi: 10.1083/jcb.84.1.184.
The availability of cultures of normal cells (NCs) and Schwann cells (SCs) with and without fibroblasts has allowed us to investigate the sources of endoneurial and perineurial constituents of peripheral nerve. NCs cultured alone, devoid of ensheathment but healthy in appearance, lack basal lamina and extracellular fibrils. In contrast, when SCs accompany NCs, basal lamina and extracellular fibrils are consistently visible around SCs in outgrowth areas formed de novo in culture. These fibrils average 18 nm in diameter, exhibit a repeating banding pattern, and are trypsin-resistant and collagenase-sensitive. Collagen synthesis is also indicated by the incorporation of [14C]proline into peptide-bound hydroxy-proline in NC + SC or SC cultures. That the [14C]hydroxyproline polypeptides formed in NC + SC cultures are collagenous was determined in part by pepsin digestion-ammonium sulfate precipitation-polyacrylamide gel electrophoresis techniques; the 14C-polypeptides migrate to the positions of alpha 1 (I), alpha 2, alpha 1 (III), and alpha B chains of type I, type III, and A-B collagens. Also formed are thin, ruthenium red-preserved strands interconnecting basal laminae. SC ensheathment of axons is similar to that found in the animal; one SC is related to a number of unmyelinated axons or a single myelinated axon. This proclivity to ensheathe and myelinate axons indicates that SC function is not lost during the preparative procedures or after lengthy isolation in culture and provides the most reliable means for SC identification. Perineurial ensheathment and macrophages are lacking in NC + SC culture preparations divested of fibroblasts. We conclude that SCs do not form perineurium or the larger diameter collagen fibrils typical of endoneurium but that in combination with neurons they generate biochemically detectable collagens and morphologically visible basal lamina and thin collagenous fibrils.
正常细胞（NCs）和成纤维细胞存在与否的雪旺细胞（SCs）培养物，使我们能够研究周围神经内膜和神经束膜成分的来源。单独培养的NCs没有被包裹，但外观健康，缺乏基膜和细胞外纤维。相比之下，当SCs与NCs一起培养时，在培养过程中重新形成的生长区域，SCs周围始终可见基膜和细胞外纤维。这些纤维平均直径为18纳米，呈现出重复的带状模式，对胰蛋白酶有抗性，对胶原酶敏感。在NC+SC或SC培养物中，[14C]脯氨酸掺入肽结合的羟脯氨酸中也表明了胶原的合成。通过胃蛋白酶消化-硫酸铵沉淀-聚丙烯酰胺凝胶电泳技术部分确定了在NC+SC培养物中形成的[14C]羟脯氨酸多肽是胶原性的；14C-多肽迁移到I型、III型和A-B型胶原的α1（I）、α2、α1（III）和αB链的位置。还形成了连接基膜的细的、钌红保存的链。SCs对轴突的包裹与在动物体内发现的相似；一个SCs与许多无髓轴突或单个有髓轴突相关。这种包裹和髓鞘化轴突的倾向表明，SCs的功能在制备过程中或在培养中长时间分离后不会丧失，并为SCs的鉴定提供了最可靠的方法。在去除成纤维细胞的NC+SC培养物制备物中缺乏神经束膜包裹和巨噬细胞。我们得出结论，SCs不形成神经束膜或内膜典型的较大直径胶原纤维，但与神经元结合时，它们会产生生物化学可检测的胶原以及形态上可见的基膜和细胶原纤维。
