Research on Regeneration of the Optic Nerve and Functional Recovery of Retinal Ganglion Cells with Regenerated Axons

成年哺乳动物视网膜神经节细胞的轴突沿着自体移植的坐骨神经延伸很长一段距离。对成年猫视网膜神经节细胞(RGCs)的形态和生理特性进行了观察，并与文献报道的结果进行了比较。两个月后，已经再生轴突的视网膜节细胞被逆行标记注入移植物中的荧光染料。4000多个标记细胞，占完整视网膜神经节细胞总数的3.0%~4.3%，分布在水平延伸的高密度区域，其模式与完整视网膜相似。体外细胞内注射HRP或荧光黄后，观察有再生轴突的RGCs的树突形态。A和g细胞的形态与正常相似，而一些β细胞的树突状突起似…。更多的是堕落。一些“未分类”的细胞不能被识别为阿尔法、贝塔或伽马细胞。通过检查局部斑块中所有荧光黄注射的细胞来评估再生细胞群中α、β和其他细胞(包括伽马和未分类细胞)的比例。α细胞的平均比例为23.9%，约为完整视网膜的6倍。β细胞的平均比例为50.3%，略高于完整视网膜。剩下的细胞(25.7%)不能被归类为α或β细胞；这一比例大约是完整视网膜中发现的一半。这些发现表明，阿尔法细胞具有最高的再生轴突成为神经移植物的能力，而不是所有类型的细胞都同样地再生轴突。在将坐骨神经移植到视神经切断的残端两个月后，用生物细胞素顺行标记再生的轴突，并在电子显微镜下观察雪旺细胞的髓鞘形成。在3个横断面移植物的511个标记轴突中，96个纤维有髓鞘。有髓纤维比例从2.8%到76%不等。平均直径。有髓纤维为1.28微米(0.71~2.47)，无髓纤维为0.76微米(0.18~2.46)。髓鞘内外径之比(g值)平均值为0.72，略小于正常成年猫视神经轴突的值(0.8)。1只猫移植物的神经纤维共记录到102个单位对受限视野刺激有反应。28个单位具有Y细胞特有的大感受野和活跃的时相反应，51个单位具有X细胞特有的小感受野和活跃的相紧张性反应，10个单位具有W细胞特有的迟缓或紧张性相反应，每类的一些例子有抑制或拮抗的环境。8个单位不能归类为Y、X或W细胞。Y(28%)、X(50%)和其他(22%)的比例与形态研究中获得的α、β和其他的比例相似。较少

Transected axons of retinal ganglion cells elongate a long distance along the autografted sciatic nerve in adult mammals. Morphological and physiological properties of retinal ganglion cells (RGCs) were examined in adult cats in order to compare the results with knowledge reported.The optic nerve of adult cats was transected and an autologous peripheral nerve was transplanted to the stump. Two months later RGCs that had regenerated their axons were retrogradely labeled with fluorescent dye injected into the graft. The more than 4,000 labeled cells, which were 3.0% to 4.3% of total ganglion cell number in the intact retina, were distributed in a high density area elongating horizontally, in a pattern similar to that observed in the intact retina.The dendritic morphology of RGCs with regenerated axons was examined after intracellular injections of HRP or Lucifer yellow in vitro. The morphology of a and g cells appeared comparable to normal, whereas the dendrites of some beta cells seemed … More to degenerate. Some "unclassified" cells could not be identified as alpha, beta, or gamma cells. The proportion of alpha,beta and other cells including gamma and unclassified in the regenerating cell population was evaluated by examining all the Lucifer yellow injected cells in local patches. The average proportion of alpha cells was 23.9%, about 6 times higher than in intact retinas. The average proportion of beta cells was 50.3%, slightly higher than in intact retinas. The remaining cells (25.7%) could not be categorized as alpha or beta ; this proportion is about half that found in intact retinas. These findings suggest that alpha cells have the highest capacity to regenerate their axon into nerve grafts, rather than all the types equally regenerate their axons.Regenerated axons were labeled anterogradely with biocytin two months after transplanting the sciatic nerve to the axotomized optic stump, and myelin formation by Schwann cells was examined electron microscopically. Among 511 labeled axons in three cross-sectioned grafts, 96 fibers were myelinated. Proportions of myelinated fibers varied from 2.8% to 76%. Mean diameter. of myelinated fibers was 1.28 mum (range 0.71-2.47) and that of unmyelinated fibers was 0.76 mum (range 0.18-2.46). Mean ratio of inner versus outer diameters of myelin sheath (g-value) was 0.72 which was a little smaller than the value (0.8) in the optic axons of intact adult cats.A total of 102 units recorded from teased fibers of a nerve graft in one cat responded to stimulation of a restricted visual field. 28 units had large receptive fields and brisk phasic responses characteristic of Y cells ; 51 units had small receptive fields and brisk phasic-tonic responses characteristic of X cells ; 10 units had sluggish phasic or tonic responses characteristic of W cells.Some examples of each category had suppressive or antagonistic surrounds. 8 units could not be classified as Y,X or W cells. The proportions of Y (28%), X(50%) and others (22%) were similar to the proportions of alpha, beta and other obtained in the morphological study. Less