Stuermer C A
J Embryol Exp Morphol. 1986 Apr;93:1-28.
This study investigates the order of regenerating retinal axons in the goldfish. The spatiotemporal pattern of axon regrowth was assessed by applying horseradish peroxidase (HRP) to regenerating axons in the optic tract at various times after optic nerve section and by analysing the distribution of retrogradely labelled ganglion cells in retina. At all regeneration stages labelled ganglion cells were widely distributed over the retina. There was no hint that axons from central (older) ganglion cells might regrow earlier, and peripheral (younger) ganglion cells later, as occurs in normal development. The absence of an age-related ordering in the regenerated optic nerve was demonstrated by labelling a few axon bundles intraorbitally with HRP (Easter, Rusoff & Kish, 1981) caudal to the previous cut. The retrogradely labelled cells in retina were randomly distributed in regenerates and not clustered in annuli as in normals. Tracing regenerating axons which were stained anterogradely from intraretinal HRP applications or retrogradely from single labelled tectal fascicles illustrated the fact that the regenerating axons coursed in abnormal routes in the optic nerve and tract. On the surface of the tectum regenerated fibres re-established a fascicle fan. The retinal origin of tectal fascicles was assessed by labelling individual peripheral, intermediate and rostral fascicles with HRP. The retrogradely labelled ganglion cells in the retina were often more widely distributed than in normals, but were mostly found in peripheral, intermediate and central retina, respectively. The order of fibre departure from each tectal fascicle was revealed by placing HRP either on the fascicle's proximal or on its distal half. With proximal labelling sites labelled ganglion cells were found in the temporal and nasal retina, and with distal labelling sites labelled ganglion cells were confined to nasal retina only. Further, the axonal trajectories of anterogradely labelled dorsotemporal retinal ganglion cells were compared to those of dorsonasal retinal ganglion cells in tectal whole mounts. Dorsotemporal axons were confined to the rostral tectal half, whereas dorsonasal axons followed fascicular routes into the fascicle's distal end and reached into caudal tectum. This suggests that the fibres exited along their fascicle's course in a temporonasal sequence. Thus in the tectum, fibres in fascicles restore a gross spatial and age-related order and tend to follow their normal temporonasal sequence of exit.
本研究调查了金鱼视网膜轴突再生的顺序。通过在视神经切断后的不同时间，将辣根过氧化物酶（HRP）应用于视束中的再生轴突，并分析视网膜中逆行标记的神经节细胞的分布，来评估轴突再生的时空模式。在所有再生阶段，标记的神经节细胞广泛分布于视网膜。没有迹象表明，来自中央（较老）神经节细胞的轴突可能比周边（较年轻）神经节细胞的轴突更早再生，而周边神经节细胞的轴突再生较晚，这与正常发育情况不同。通过用HRP（伊斯特、鲁索夫和基什，1981年）在眶内标记先前切口尾部的一些轴突束，证明了再生视神经中不存在与年龄相关的顺序。视网膜中逆行标记的细胞在再生组织中随机分布，不像正常情况下那样聚集在环带中。追踪从视网膜内HRP顺行染色或从单个标记的顶盖束逆行染色的再生轴突，说明了再生轴突在视神经和视束中走行异常的事实。在顶盖表面，再生纤维重新形成了一个束状扇形。通过用HRP标记单个周边、中间和 Rostral 束，评估了顶盖束的视网膜起源。视网膜中逆行标记的神经节细胞分布通常比正常情况更广泛，但大多分别位于周边、中间和中央视网膜。通过将HRP置于束的近端或远端一半，揭示了从每个顶盖束发出的纤维顺序。近端标记部位时，在颞侧和鼻侧视网膜中发现了标记的神经节细胞，而远端标记部位时，标记的神经节细胞仅局限于鼻侧视网膜。此外，在顶盖整装片中，比较了顺行标记的背颞侧视网膜神经节细胞和顺行标记的背鼻侧视网膜神经节细胞的轴突轨迹。背颞侧轴突局限于顶盖的 Rostral 半部，而背鼻侧轴突沿着束状路径进入束的远端并延伸至尾侧顶盖。这表明纤维沿着其束的走行以颞鼻顺序离开。因此，在顶盖中，束中的纤维恢复了大致的空间和与年龄相关的顺序，并倾向于遵循其正常的颞鼻离开顺序。
