Bohn R C, Stelzner D J
J Comp Neurol. 1981 Mar 10;196(4):605-20. doi: 10.1002/cne.901960407.
We have reported previously that during optic nerve regeneration in Rana pipiens, axons are misrouted into the opposite nerve and retina. In the present investigation we have examined the time course of formation of these "misrouted" axons and their cells of origin. The right eye of 31 frogs was injected with 3H-proline at various times after right optic nerve crush. In every frog examined 2 weeks and later after nerve crush, the distribution of autoradiographic label indicated that axons from the right eye had grown into the left optic nerve at the chiasm. The amount of label increased from 2 weeks to reach a maximum at 6 weeks where the entire left nerve was filled with silver grains. At 5 to 6 weeks after crush, labeled axons were found within the ganglion cell fiber layer (GCFL) of the retina of the opposite eye for a maximum distance of 2.3 mm from the optic disc. In frogs examined at intervals later than 6 weeks after crush, the amount of label within the left eye and nerve progressively decreased, indicating a gradual disappearance of the misrouted axons. Studies using anterograde transport of horseradish peroxidase (HRP) after nerve injection confirmed these autoradiographic findings. The position of ganglion cells in the right eye whose axons were misrouted to the left eye was determined by retrograde transport of HRP. Five or 6 weeks after crushing the right optic nerve, the left eye was injected with HRP and labeled ganglion cells were found throughout the right eye retina. The largest percentage of labeled cells was found within the ventral half of the retina, particularly within the temporal quadrant, and nearly all of the labeled cells were found in more peripheral portions of the retina. Since few retino-retinal axons are found during normal development, the present results show that the factors guiding regenerating axons in the adult frog differ substantially from those present during development.
我们之前报道过，在牛蛙视神经再生过程中，轴突会误入对侧神经和视网膜。在本研究中，我们检查了这些“误入歧途”的轴突及其起源细胞的形成时间进程。在右侧视神经挤压后的不同时间，向31只青蛙的右眼注射3H-脯氨酸。在每只于神经挤压后2周及更晚时间检查的青蛙中，放射自显影标记的分布表明，右眼的轴突已在视交叉处长入左侧视神经。标记量从2周开始增加，在6周时达到最大值，此时整个左侧神经都布满了银粒。在挤压后5至6周，在对侧眼视网膜的神经节细胞纤维层（GCFL）内发现了标记轴突，距视盘的最大距离为2.3毫米。在挤压后6周以后的不同时间间隔检查的青蛙中，左眼和神经内的标记量逐渐减少，表明误入歧途的轴突逐渐消失。在神经注射后使用辣根过氧化物酶（HRP）的顺行运输进行的研究证实了这些放射自显影结果。通过HRP的逆行运输确定了轴突误入左眼的右眼神经节细胞的位置。在右侧视神经挤压5或6周后，向左眼注射HRP，在整个右眼视网膜中发现了标记的神经节细胞。标记细胞的最大百分比出现在视网膜的腹侧半部分，特别是在颞侧象限，并且几乎所有标记细胞都位于视网膜的更周边部分。由于在正常发育过程中很少发现视网膜-视网膜轴突，目前的结果表明，指导成年青蛙再生轴突的因素与发育过程中存在的因素有很大不同。
