Thompson I D, Cordery P, Holt C E
University Laboratory of Physiology, Oxford, United Kingdom.
J Comp Neurol. 1995 Jun 26;357(2):181-203. doi: 10.1002/cne.903570202.
Anterograde and retrograde tracing techniques have been used to study the uncrossed retinal projection in neonatal pigmented and albino Syrian hamsters. The total number of retinal ganglion cells projecting ipsilaterally peaks at postnatal days 2-4 (P2-P4) and declines to adult values by P12. The change in cell numbers has a similar time course in albino and pigmented animals. Although the population of uncrossed cells in the temporal retina of albino hamsters is always less than that in pigmented hamsters, no difference between the colour phases was found for the population of uncrossed cells in nasal retina. Differential cell death also contributes to the adult albino decussation pattern in hamsters: The relative loss of cells from temporal retina in albinos (72%) is greater than that in pigmented animals (56%). The additional loss in albinos does not appear to depend on binocular interactions: The same proportion (30%) of uncrossed cells is "rescued" from death by neonatal monocular enucleation in both colour phases. Flat-mount preparations showing the distribution of uncrossed fibres reveal that a distinct focus of terminals emerges in rostral superior colliculus, which is topographically appropriate for a binocular mapping, at the peak of uncrossed ganglion cell numbers (P4). Comparison of uncrossed terminal distributions and ganglion cell death reveals considerable refinement of the terminals prior to the main phase of cell death. Monocular enucleations performed some time after birth have a greater effect on uncrossed terminal distributions than on cell death. These observations suggest that independent mechanisms may be involved in the regulation of terminal distributions and of cell numbers in the developing uncrossed retinal pathways.
顺行和逆行追踪技术已被用于研究新生有色和白化叙利亚仓鼠的未交叉视网膜投射。同侧投射的视网膜神经节细胞总数在出生后第2 - 4天（P2 - P4）达到峰值，并在P12时降至成年水平。白化和有色动物的细胞数量变化具有相似的时间进程。尽管白化仓鼠颞侧视网膜中未交叉细胞的数量总是少于有色仓鼠，但在鼻侧视网膜中未交叉细胞的数量在不同毛色阶段之间未发现差异。差异性细胞死亡也导致了仓鼠成年白化动物的交叉模式：白化动物颞侧视网膜细胞的相对损失（72%）大于有色动物（56%）。白化动物的额外损失似乎不依赖于双眼相互作用：在两个毛色阶段，相同比例（30%）的未交叉细胞通过新生单眼摘除术从死亡中“挽救”下来。显示未交叉纤维分布的平铺标本显示，在未交叉神经节细胞数量达到峰值（P4）时，在 Rostral 上丘出现了一个明显的终末焦点，其在地形上适合双眼映射。未交叉终末分布与神经节细胞死亡的比较显示，在细胞死亡的主要阶段之前，终末有相当程度的精细化。出生后一段时间进行的单眼摘除术对未交叉终末分布的影响比对细胞死亡的影响更大。这些观察结果表明，独立的机制可能参与了发育中未交叉视网膜通路中终末分布和细胞数量的调节。
