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横断轴突沿自体移植的坐骨神经延伸沿着很长的距离。为了解成年猫视网膜神经节细胞（retinal ganglion cells，RGCs）的形态学和生理学特性，将成年猫视神经切断，自体周围神经移植于断端。两个月后，将荧光染料注射到移植物中，逆行标记再生轴突的RGCs。标记细胞4,000多个，占完整视网膜神经节细胞总数的3.0%~ 4.3%，呈水平延伸的高密度区分布，与完整视网膜相似。a和g细胞的形态与正常细胞相似，而一些β细胞的树突似乎 ...更多信息 堕落一些“未分类”的细胞不能被鉴定为α、β或γ细胞。通过检查局部贴片中所有荧光黄注射细胞，评价再生细胞群中α、β和其他细胞（包括γ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。剩余的细胞（25.7%）不能归类为α或β;这个比例大约是完整视网膜中发现的一半。这些发现表明，α细胞具有最高的能力，再生轴突成神经移植物，而不是所有类型的平等再生axons. reproduced轴突顺行标记biocytin两个月后，移植坐骨神经的轴突切断视神经残端，和髓鞘形成的许旺细胞进行了电子显微镜检查。在三个横切移植物中的511个标记的轴突中，96个纤维有髓鞘。有髓纤维的比例从2.8%到76%不等。平均直径。有髓纤维为1.28 μ m（范围0.71-2.47），无髓纤维为0.76 μ m（范围0.18-2.46）。结果表明，正常成年猫视神经轴突髓鞘内外径之比（g值）为0.72，略小于正常成年猫视神经轴突的g值（0.8）。28个单位感受野大，相位反应快，具有Y细胞的特征; 51个单位感受野小，相位-紧张反应快，具有X细胞的特征; 10个单位感受野小，相位或紧张反应慢，具有W细胞的特征。8个单元无法归类为Y、X或W单元。Y（28%）、X（50%）和其他（22%）的比例与形态学研究中获得的α、β和其他的比例相似。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