Lowenger E, Levine R L
Department of Biology, McGill University, Montréal, Québec, Canada.
J Comp Neurol. 1988 May 15;271(3):319-30. doi: 10.1002/cne.902710303.
We have studied the early stages (4-14 days) of axonal regeneration following intraorbital optic nerve crush in the goldfish. We used 3H-proline autoradiography to anterogradely label and visualize the growing axons and wheat germ agglutinin-conjugated horseradish peroxidase (WGA:HRP) for retrograde labeling to determine the cells of origin of the earliest projections. The first retinal ganglion cells (RGCs) that could be retrogradely filled from the optic tract, following optic nerve crush, were in the central retina and were seen at 8 days postoperative. More peripheral cells were only labeled with longer postcrush survival periods. Thus, the first axons to regenerate past the lesion were from central RGCs. The axons of these cells extended into the cranial nerve stump between 4 and 5 days postcrush and entered the nerve as a fascicle, which travelled just beneath its surface. Studies of nerve cross sections from animals at 5-8 days postoperative demonstrated that initial outgrowth was not confined to any particular locale within the nerve although the early fibers appeared to avoid its temporal aspect. When the regenerating axons reached the optic tract they remained in fascicles but left the surface to run along the medial, deep portion of the tract, immediately adjacent to the diencephalon and pretectum. The positions occupied by the earliest-regenerating axons in the optic nerve were variable and not always appropriate for their central retinal origin. However, the abrupt change in growth trajectory as the fibers entered the optic tract brought them into the areas of the visual paths that are occupied by central axons in intact animals. We suggest that this change in position is related to both changes in the structural organization of the intracranial visual paths and to possible axon guidance signals in the region of the nerve-tract juncture.
我们研究了金鱼眶内视神经挤压伤后轴突再生的早期阶段（4 - 14天）。我们使用³H - 脯氨酸放射自显影术对生长中的轴突进行顺行标记和可视化，并使用小麦胚凝集素结合辣根过氧化物酶（WGA:HRP）进行逆行标记，以确定最早投射的起源细胞。视神经挤压伤后，最早能从视束逆行填充的视网膜神经节细胞（RGCs）位于视网膜中央，术后8天可见。更多外周细胞只有在挤压伤后存活时间更长时才被标记。因此，最早再生越过损伤部位的轴突来自中央RGCs。这些细胞的轴突在挤压伤后4至5天延伸到颅神经残端，并作为一束纤维进入神经，该束纤维在神经表面下方运行。对术后5 - 8天动物的神经横断面研究表明，最初的生长并不局限于神经内的任何特定区域，尽管早期纤维似乎避开了神经的颞侧部分。当再生轴突到达视束时，它们仍成束状，但离开表面，沿着视束内侧深部运行，紧邻间脑和顶盖前区。最早再生的轴突在视神经中占据的位置各不相同，并不总是与其视网膜中央起源相适应。然而，当纤维进入视束时生长轨迹的突然变化使它们进入了完整动物中由中央轴突占据的视觉通路区域。我们认为这种位置变化与颅内视觉通路结构组织的变化以及神经束交界处区域可能的轴突导向信号有关。
