Procrsses of degeneration and regeneration of retinal ganglion cells of the mammalian retina after axonal injury

我们研究了成年大鼠视网膜axocut视网膜神经节细胞（RCGs）的三维树突形态、突触结构和营养因子对其的影响。90天大的动物在眼睛后面被切开，大约30天用于实验。为了从三维角度观察树突形状，将路西法染料注射到4SPdiI逆行标记的RCGs细胞内，并用激光扫描共聚焦显微镜对样品进行分析。电镜观察采用光氧化法或神经生物素注射法。眼内注射各种神经营养因子，通过计算视网膜神经节细胞的存活率来测定其作用。通过实验，得到了以下一些结果。1)长时间切除后存活的视网膜神经节细胞胞体直径大于20 μ m，其树突状形态暗示其为α神经节细胞来源。2)大多数存活的神经节细胞的树突状树长度比正常的α神经节细胞的树突状树长20%。3)神经生物素注射显示，许多注射后的离体神经节细胞显示出示踪偶联，且这种偶联主要发生在邻近的无突细胞中。4)存活时间较长的神经节细胞内核层或神经节细胞层的某些细胞类型之间存在间隙连接。5)部分神经营养因子能有效促进轴突生长，但不能提高RGC切除后的存活率。

We studied the three-dimensional dendritic morphology, synaptic structure and the effects of nutritional factors on the axotomized retinal ganglion cells (RCGs) in the adult rat retina. The animals of 90 days old were axotomized right behind the eye and left about 30 days for the experiments. To observe dendritic shape 3-dimensionally, lucifer dye was injected intracellularly to the RCGs retrogradely-labeled with 4SPdiI and such specimens were subjected to analyze by using laser scanning confocal microscope. For the electron microscopic study, photooxidation of lucifer or neurobiotin injection metod were used. Various neurotrophic factors were injected intraocularly and the effects were measured by counting the survival of the retinal ganglion cells. By the experiments, some results described below were obtained. 1) the survived retinal ganglion cells after axotomy for a long period of time exhibit larger soma diameter more than 20 um and their dendritic shape implied them as alpha ganglion cell origin. 2) Most of the ganglion cells survived showed larger dendritic tree length as much as 20% of that of normal alpha ganglion cells locating in the same retinal eccentricity. 3) Neurobiotin injection revealed that many of the injected axtomized ganglion cells show tracer-coupling and the coupling was mainly occurred in the neighboring amacrine cells. 4) The ganglion cells long survived were found to have gap junction between certain cell types either in the inner nuclear layr or ganglion cell layr. 5) Some neurotrophic factors were effective to accelerate axonal outgrowth but did not increase survival ratio of RGC after axotomy.