Raven Mary A, Reese Benjamin E
Neuroscience Research Institute and Department of Psychology, University of California at Santa Barbara, Santa Barbara, California 93106-5060, USA.
J Comp Neurol. 2002 Dec 9;454(2):168-76. doi: 10.1002/cne.10444.
The present study has examined the density and mosaic regularity of the population of horizontal cells in the pigmented and albino mouse retina. Retinal wholemounts were immunostained for calbindin, and labeled cells within sampled fields were analyzed to determine horizontal cell soma size and density. The X-Y positional coordinates of each cell were determined, from which the geometrical properties of the mosaic were examined using nearest neighbor and Voronoi domain analyses, and regularity indices were derived from those measures. Autocorrelation and density recovery profile analyses were also conducted to identify the presence of exclusion zones within the population of horizontal cells. For each sampled field, random simulations of matched density, constrained by the physical size of the horizontal cells, were generated and analyzed in parallel. Neither retinal area, nor horizontal cell soma size, nor density differed between the pigmented and albino retinas. Mosaic regularity in pigmented and albino retinas did not differ, but each differed significantly from random simulations of identical density. Horizontal cells in the mouse retina exhibit exclusion zones extending beyond the physical size of the soma, but these were identical in size in the pigmented and albino retina. Such exclusion zones are suggested to reflect homotypic interactions between horizontal cells during early development that mediate cellular repulsion and tangential movement. The lack of any discernable effect brought about by the albino mutation, despite numerous developmental abnormalities associated with the retinal neuroepithelium in albino mice, is consistent with other results showing that homotypic interactions are sufficient for the genesis of the global patterning characteristic of mature retinal mosaics.
本研究检测了有色和白化小鼠视网膜中水平细胞群体的密度和镶嵌规则性。视网膜全层标本用钙结合蛋白进行免疫染色，并对采样区域内的标记细胞进行分析，以确定水平细胞胞体大小和密度。确定每个细胞的X-Y位置坐标，据此使用最近邻和Voronoi域分析来检测镶嵌的几何特性，并从这些测量值中得出规则性指数。还进行了自相关和密度恢复剖面分析，以确定水平细胞群体中是否存在排斥区。对于每个采样区域，生成并并行分析了受水平细胞物理大小限制的匹配密度随机模拟。有色和白化视网膜在视网膜面积、水平细胞胞体大小或密度方面均无差异。有色和白化视网膜的镶嵌规则性没有差异，但与相同密度的随机模拟相比，两者均有显著差异。小鼠视网膜中的水平细胞表现出超出胞体物理大小的排斥区，但在有色和白化视网膜中，这些排斥区的大小相同。这些排斥区被认为反映了早期发育过程中水平细胞之间的同型相互作用，这种相互作用介导了细胞排斥和切向运动。尽管白化小鼠的视网膜神经上皮存在许多发育异常，但白化突变并未产生任何可察觉的影响，这与其他结果一致，即同型相互作用足以形成成熟视网膜镶嵌的全局模式特征。
