MELANIN AND THE REGULATION OF MAMMALIAN PHOTORECEPTOR TOPOGRAPHY
MELANIN AND THE REGULATION OF MAMMALIAN PHOTORECEPTOR TOPOGRAPHY
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DOI：
10.1111/j.1460-9568.1994.tb00311.x
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发表时间：
1994-04-01
影响因子：
3.4
通讯作者：
WHITMORE, A
中科院分区：
文献类型：
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作者：
JEFFERY, G;DARLING, K;WHITMORE, A
黑色素或与其直接相关的产物调节神经视网膜的成熟，因为在色素减少的哺乳动物中，中央视网膜无法完全发育。为了确定这种缺陷是否反映在光感受器的分布中，我们研究了正常饲养的色素雪貂和白化雪貂以及在弱光条件下饲养的动物的视网膜地形图。在两个品系中，视杆细胞和视锥细胞的总体分布与猫相似，视锥细胞密度在视网膜中央达到峰值，视杆细胞密度在中心区周围的环状区域达到峰值。视锥种群以有序镶嵌的形式组织，其规律性是在大范围的视网膜偏心率下测量的。无论是在中心区还是在更多的周边区域，在色素菌株和白化菌株之间，无论是在中心区还是在更多的外围区域，都没有发现锥体数量或其镶嵌分布的差异。在这两种情况下，视锥马赛克内的顺序与细胞密度或视网膜偏心率无关。在白化动物中，与有色动物的视杆数量相比，所有视网膜位置的视杆数量明显不足。在这方面，无论是在品系内部还是品系之间，正常饲养的动物和黑暗饲养的动物之间都没有差异。因此，白化病基因必须对这种细胞类型在视网膜外层的发育具有选择性和特异性的影响。神经节细胞和视杆细胞都受到白化基因的影响，而视锥细胞则不受影响。由于视锥细胞和神经节细胞是在同一时期产生的，而杆状细胞是在较晚的时期产生的，因此白化基因不能在特定的发育时间窗口中发挥作用。由于视锥马赛克在白化患者中是正常的，尽管视杆缺失很大，但调节视锥间距的因素不能以任何显著的方式依赖于后代和随后视杆添加到视网膜外部。
Melanin, or products directly associated with it, regulates the maturation of the neural retina because in hypopigmented mammals the central retina fails to develop fully. To determine whether this deficit is reflected in the distribution of photoreceptors, their topography has been studied in the retinae of normally reared pigmented and albino ferrets and animals reared under reduced light conditions. In both strains, the general distribution of rods and cones was similar to that in the cat, cone density peaking in the central retina and rod density peaking in an annulus around the area centralis. The cone population was organized in the form of an orderly mosaic whose regularity was measured at a wide range of retinal eccentricities. No differences were found in cone numbers or their mosaic distribution between pigmented and albino strains, either at the area centralis or at more peripheral regions. In both cases order within the cone mosaic was independent of cell density or retinal eccentricity. In the albinos there was a significant deficit in the number of rods at all retinal locations when compared with rod numbers in the pigmented animals. There were no differences between normally reared and dark-reared animals in this respect either within or between the strains. Therefore, the albino gene must have a selective and specific effect on the development of this cell type in the outer retina. Ganglion cells and rods are both affected by the albino gene, while cones are not. Because cones and ganglion cells are generated during the same period and rods are generated later, the albino gene cannot be acting during a particular developmental time window. Because the cone mosaic was normal in the albinos, in spite of a large rod deficit, the factors that regulate the spacing of cones cannot depend in any significant manner upon the later generation and subsequent addition of rods to the outer retina.