本研究探討線鱧(Channa striata)之視網膜細胞拓譜與其空間解析度。實驗使用五隻線鱧為樣本，經MS-222麻醉後以磷酸鹽緩衝生理食鹽水和中性福馬林固定液灌流犧牲，取得眼球樣本。視網膜經過全包埋(wholemount)後觀察視錐細胞(cone cell)並將結果輸入R語言撰寫之程式進行分析。研究結果顯示，線鱧之視網膜拓譜具有一明顯的視覺帶(visual streak)和顳區(area temporalis)，可以推論線鱧之視覺對於水平線和正前方之立體視覺空間解析度較佳。線鱧之視錐細胞數量每平方公釐約有2602至37982個細胞，平均±標準差為每平方公釐12763±5002個細胞，與前人研究結果相比，線鱧錐細胞的密度低於目前已知的多種日行性魚類，此結果符合其晨昏活動之習性。視錐細胞以2+2+1之形式形成一方陣排列，由四個雙視錐細胞(double cone)包圍一個單視錐細胞(single cone)組成一個方陣單位，這類錐細胞排列方式較常出現在掠食動物之視網膜，此結果支持線鱧明顯的掠食習性。五個體神經節細胞之密度最高平均±標準差為每平方公釐10391±304個細胞，且顳區之密度分布較視錐細胞明顯。根據前人研究之公式，視錐細胞之密度最高可提供約每度5.92週期之空間解析度，而神經節細胞則可提供每度3.76週期之空間解析度。綜觀其他魚類，此組數據並不特別突出，推測應與其晨昏活動之習性和棲息環境有關。這兩組數據由組織學方式獲得，應視為最高理論值。線鱧之視錐細胞對神經節細胞之匯聚比(convergence ratio)在不同的特化區域有不同的比例，高密度區域之匯聚比較低密度者低。與水生魚類和陸生動物相比，線鱧之數據相對較低，對偵測移動之物體較為有利。

The aim of this research is to investigate the retinal cell topography and the visual acuity of the striped snakehead fish (Channa striata). Five snakehead fish were collected, anaesthetized with MS-222 and euthanized with perfusion of PBS followed by 4% paraformaldehyde in PBS. The eyeballs were collected for retinal whoulmount to observe the cone cell mosaic and the density distribution of both cone cells and retinal ganglion cells. The data were input into R scripts for further analysis. The results indicated a visual streak and area temporalis specialization on the retina. The snakehead fish might achieve better acuity on the horizon and the front. The densities of the cone cells fell in a 2602 to 37982 cells/mm2 interval and the average was 12763±5002 cells/mm2.Compared to former researches, the cell densities were intermediate, supported its crepuscular behavior. The cone cells were arranged in a 2+2+1 array. A single cone is surrounded by four double cones which result in a square lattice. The result agreed its aggressive hunting behavior. The peak density of the retinal ganglion cell is 10391±304 cells/mm2. The areae temporalis formed by the ganglion cells are more obvious than the cone cells. The peak resolution measured by the cone cells is 5.92 c/deg, while the acuity based on the retinal ganglion cells is 3.76 c/deg. The data were similar to other freshwater teleosts, it was hypothesized that the environmental factors, such as the turbidity and the light conditions were crucial thus restricted the resolution. The visual acuities were derived from histological measurements, therefore the values should be considered as the upper limit. Combine the cone and retinal ganglion cell counts, the convergence ratios were significantly higher at the area of high visual acuity in comparison with that of low density area. The ratio of the striped snakehead fish was lower than some known freshwater species. In previous studies, the low convergence ratio was beneficial for motion detection which was an important visual function for the striped snakehead fish.

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