Morgan J E, Henderson Z, Thompson I D
Neuroscience. 1987 Feb;20(2):519-35. doi: 10.1016/0306-4522(87)90108-4.
The decussation patterns of retinal ganglion cells in adult pigmented and albino ferrets were determined from the distribution of cells labelled after large unilateral injections of horseradish peroxidase into the visual pathway, involving the lateral geniculate nucleus and fibres of passage to the superior colliculus. About 6000 retinal ganglion cells project ipsilaterally in pigmented ferrets compared with only about 1500 in albino ferrets. In both strains, the vast majority of these cells (99 and 87% in pigmented and albino animals, respectively) are located in the temporal crescent, although we describe one albino ferret in which an aberrant uncrossed projection arises from nasal retina. In pigmented ferrets, there is a sharp nasotemporal division that runs through the area centralis; a small proportion of the ganglion cells in temporal crescent (less than 10%) does project contralaterally. In albinos, however, the majority of cells in temporal retina project contralaterally. There is no clear nasotemporal division in the albino retina; the density of uncrossed ganglion cells is reduced throughout temporal crescent and at no location exceeds the comparable density of the crossed projection. The peak density within the reduced uncrossed projection is also displaced away from the area centralis into temporal retina. Analysis of cell type on the basis of soma size indicates that whereas large horseradish peroxidase injections into the visual pathway of pigmented ferrets label all types of ganglion cell in the crossed projection, injections restricted to the superior colliculus label only those ganglion cells with large or small somata. The distribution of cell sizes in the crossed projection from temporal retina is biased towards small cells in the pigmented ferret but in albinos resembles that seen in the crossed projection from nasal retina. Thus the adult pigmented ferret has both a well developed nasotemporal division in which decussation lines are obvious in the crossed and uncrossed pathways and also, unlike rodents but like cats, a class of ganglion cell that does not project to the superior colliculus. The albino mutation both reduces the uncrossed projection throughout temporal retina, although the reduction is greatest close to the area centralis, and also commensurately increases the crossed projection from temporal retina.
通过向视觉通路（包括外侧膝状体核以及通向中脑上丘的纤维束）进行单侧大剂量辣根过氧化物酶注射后标记细胞的分布情况，确定了成年有色和白化雪貂视网膜神经节细胞的交叉模式。在有色雪貂中，约有6000个视网膜神经节细胞向同侧投射，而在白化雪貂中只有约1500个。在这两个品系中，这些细胞的绝大多数（有色和白化动物中分别为99%和87%）位于颞侧月牙区，不过我们描述了一只白化雪貂，其异常的不交叉投射起源于鼻侧视网膜。在有色雪貂中，有一条穿过中央凹区域的明显鼻颞分界线；颞侧月牙区中一小部分神经节细胞（不到10%）确实向对侧投射。然而，在白化雪貂中，颞侧视网膜中的大多数细胞向对侧投射。白化雪貂视网膜中没有明显的鼻颞分界线；整个颞侧月牙区不交叉神经节细胞的密度降低，且在任何位置都不超过交叉投射的可比密度。在降低的不交叉投射中，峰值密度也从中央凹区域移向颞侧视网膜。根据胞体大小对细胞类型进行分析表明，虽然向有色雪貂的视觉通路中大量注射辣根过氧化物酶会标记交叉投射中的所有类型神经节细胞，但仅局限于中脑上丘的注射仅标记那些胞体大或小的神经节细胞。在有色雪貂中，来自颞侧视网膜的交叉投射中细胞大小的分布偏向于小细胞，而在白化雪貂中则类似于来自鼻侧视网膜的交叉投射中所见的情况。因此，成年有色雪貂既有发育良好的鼻颞分界线，在交叉和不交叉通路中交叉线都很明显，而且与啮齿动物不同但与猫一样，有一类不投射到中脑上丘的神经节细胞。白化突变既减少了整个颞侧视网膜的不交叉投射，尽管在靠近中央凹区域减少最大，同时也相应增加了来自颞侧视网膜的交叉投射。
