Fitzgibbon T, Taylor S F
Department of Clinical Ophthalmology, University of Sydney, New South Wales, Australia.
J Comp Neurol. 1996 Nov 11;375(2):238-51. doi: 10.1002/(SICI)1096-9861(19961111)375:2<238::AID-CNE5>3.0.CO;2-3.
The organisation of the primate nerve fibre layer and optic nerve head with respect to eccentricity or the positioning of central and peripheral axons remains controversial. Crystals of the carbocyanine dyes DiI (1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate), or DiA (4-[4-didecylaminostryryl]-N-methylpridiniumiodide) were used to trace retinal ganglion cell axons within the nerve fibre layer, optic nerve head, and optic nerve. The present study demonstrated that peripheral retinal axons were scattered throughout the vitreal-scleral depth of the nerve fibre layer. This scattered distribution was maintained as the fibres passed through the optic nerve head and into the optic nerve. Axons of the arcuate bundles showed a bias towards the scleral portions of the nerve fibre layer and a variable degree of fibre scatter across the nerve fibre layer which was not as evident in labelling from other retinal regions. There was a rough topographic representation within the optic nerve head according to retinal circumference such that both peripheral and central fibres were mixed within a wedge extending from the periphery to the centre of the nerve. Foveal fibres occupied a large proportion of the temporal aspect of the optic nerve head and nerve, whereas fibres from areas temporal to the fovea appeared to be displaced to more superior and inferior regions. Consistent with the scleral bias seen in the retina, arcuate fibres maintained a peripheral position as they passed through the optic nerve head and occupied a more peripheral position in the nerve. The present results suggest that any degree of order present within the optic nerve is not an active process; optic axons are not instructed to establish a retinotopic order within the initial portions of the visual pathway.
灵长类动物神经纤维层和视神经乳头关于离心率或中央与外周轴突定位的组织方式仍存在争议。使用碳菁染料DiI（1,1'-二辛基-3,3,3',3'-四甲基吲哚碳菁高氯酸盐）或DiA（4-[4-二癸基氨基苯乙烯基]-N-甲基碘化吡啶）的晶体来追踪神经纤维层、视神经乳头和视神经内的视网膜神经节细胞轴突。本研究表明，外周视网膜轴突散布于神经纤维层的玻璃体-巩膜深度范围内。当纤维穿过视神经乳头并进入视神经时，这种散布分布得以维持。弓形束的轴突偏向神经纤维层的巩膜部分，并且在整个神经纤维层上有不同程度的纤维散布，这在来自视网膜其他区域的标记中不那么明显。根据视网膜周长，在视神经乳头内存在大致的地形图表示，使得外周和中央纤维在从周边延伸至神经中心的楔形区域内混合。黄斑纤维占据视神经乳头和神经颞侧的很大一部分，而来自黄斑颞侧区域的纤维似乎移位到了更上和更下的区域。与在视网膜中看到的巩膜偏向一致，弓形纤维在穿过视神经乳头时保持外周位置，并在神经中占据更外周的位置。目前的结果表明，视神经内存在的任何程度的有序性都不是一个主动过程；视觉轴突在视觉通路的初始部分并没有被指示去建立视网膜拓扑顺序。
