双荧光逆向追踪法研究大鼠视网膜节细胞的中枢投射

Retrograde fluorescent double-labeling study of distribution and projection of rat retinal ganglion cells

目的：观察向上丘投射的大鼠视网膜神经节细胞(RGCs)在视网膜内的分布、密度及细胞类型上的差异。方法：将 DiI 与荧光金(FG)注射入 SD 大鼠的同侧和(或)对侧上丘,不同时相荧光显微镜下观察两种荧光标记 RGCs 的分布情况。结果：视网膜与视神经内均可见荧光标记；视网膜内标记 RGCs 的数目随时间延长略有增加。DiI 与 FG 的标记效率无明显差异；RGCs 大多数为对侧投射；视网膜颞背侧区域可见双侧投射细胞；视网膜颞腹侧周边区集中存在同侧投射细胞,多数胞体较大；视网膜其它区域可见零星同侧投射细胞。结论：DiI 与 FG 可高效率逆行标记 RGCs 及部分突起；SD 大鼠视网膜内并存着向对侧、双侧及同侧脑区投射的 RGCs,后二者数量较少,分布局限；同侧投射以大胞体细胞为多。

Objective： To study the number, topographic distribution and soma size of retinal ganglion cells （RGCs） according to their projection targets by retrograde fluorescent double-labeling the superior colliculus （SC） in adult rats. Methods： The retrograde fluorescent neuronal tracer DiI or fluoro-gold（FG） was injected into the ipsilateral and contralateral SC, then rats were killed and the fluorescent distribution in the retinae and optic nerves were observed under fluorescence microscope and the labeled RGCs were counted. Results： Fluorescence was observed in the sections of retinae and optic nerves. The labeled RGCs in the retinae increased gradually with labeling time, but the mean cell count was not significantly different between FG and. DiI groups. Most of labeled RGCs projected contralaterally and double-labeled cells were mainly seen in the temporal retina while iPsilaterally projected RGCs were mainly confined to the peripheral temporoventral quarter of the retina. Sparse cells were found in other quarters; most of them tended to have bright branches and larger soma. Conclusion： Both FG and DiI can efficiently label the soma and part branches of RGCs. Contralateral, bilateral and ipsilateral projected RGCs coexist in the retina of rat; most of them are contralaterally projected. Ipsilateraily projected RGCs are mainly large sized cells.