Osawa T, Tohyama K, Ide C
Department of Oral Anatomy, School of Dentistry, Iwate Medical University, Morioka, Japan.
J Neurocytol. 1990 Dec;19(6):833-49. doi: 10.1007/BF01186814.
The role of basal laminae as conduits for regenerating axons in an allogeneic graft was examined by transplanting a 3 cm long segment of the sciatic nerve from the Brown Norway to the Fischer 344 strain of rat. These strains are not histocompatible with each other. In order to compare the nerve regeneration in variously treated grafts, three different types of graft were employed: non-treated (NT), predenervated (PD), and predenervated plus freeze-treated (PDC) grafts. The cytology of nerve regeneration through these grafts was examined by electron microscopy at four, seven, 14, 30 and 60 days after grafting. In the PDC graft, in which Schwann cells were dead on grafting, basal laminae were well preserved in the form of tubes after Schwann cells and myelin sheaths had been removed at seven days after grafting. Regenerating axons accompanied by immature host Schwann cells grew out through such basal lamina tubes in the same fashion as observed in our previous studies. By day 14, axons extended as far as the middle of the graft. In the proximal part they were separated into individual fibres and even thinly myelinated by Schwann cells. On the other hand, in the NT and PD grafts in which Schwann cells were alive on grafting, most Schwann cells and myelin sheaths appeared to undergo autolytic degeneration by day 14, while Schwann cell basal laminae were left almost intact in the form of tubes. A few regenerating axons were seen associated with Schwann cells in the proximal portion by day seven. It is probable that host Schwann cells moved into the graft after donor cells had been degraded. Schwann cell basal laminae tended to be damaged at the site of extensive lymphoid cell infiltration. By day 30, regenerating axons had arrived at the distal end of the graft in all three types of graft: in the PDC graft thick axons were fully myelinated, whereas in the PD graft they were only occasionally myelinated and in the NT graft most axons were still surrounded by common Schwann cells. By 60 days after grafting, regenerating axons were well myelinated in the host nerve as observed 1 cm distal to the apposition site in all the three types of graft. These findings show that Schwann cell basal laminae can serve as pathways (most efficiently in the PDC graft) for regenerating axons in a 3 cm long allograft in the rat.
通过将一段3厘米长的棕色挪威大鼠坐骨神经移植到费希尔344大鼠品系中，研究了基底膜在同种异体移植中作为再生轴突通道的作用。这两个品系彼此组织不相容。为了比较不同处理的移植物中的神经再生情况，采用了三种不同类型的移植物：未处理（NT）、预先去神经（PD）和预先去神经加冷冻处理（PDC）移植物。在移植后第4、7、14、30和60天，通过电子显微镜检查通过这些移植物的神经再生的细胞学情况。在PDC移植物中，施万细胞在移植时已死亡，在移植后7天施万细胞和髓鞘被去除后，基底膜以管状形式保存完好。再生轴突伴随着未成熟的宿主施万细胞以与我们先前研究中观察到的相同方式通过这种基底膜管生长出来。到第14天，轴突延伸到移植物中部。在近端，它们分离成单个纤维，甚至被施万细胞轻度髓鞘化。另一方面，在移植时施万细胞存活的NT和PD移植物中，到第14天大多数施万细胞和髓鞘似乎发生自溶变性，而施万细胞基底膜几乎完整地以管状形式保留。到第7天，在近端部分可见少数再生轴突与施万细胞相关联。很可能在供体细胞降解后宿主施万细胞移入移植物。施万细胞基底膜在广泛淋巴细胞浸润部位往往受损。到第30天，再生轴突在所有三种类型的移植物中都到达了移植物的远端：在PDC移植物中粗轴突完全髓鞘化，而在PD移植物中它们只是偶尔髓鞘化，在NT移植物中大多数轴突仍被普通施万细胞包围。移植后60天，在所有三种类型的移植物中，在对接部位远端1厘米处观察到再生轴突在宿主神经中髓鞘化良好。这些发现表明，施万细胞基底膜可以作为大鼠3厘米长同种异体移植物中再生轴突的通道（在PDC移植物中效率最高）。
