Hailman J P
J Morphol. 1976 Apr;148(4):453-68. doi: 10.1002/jmor.1051480404.
Oildroplets in the eyes of terrestrial vertebrates are spherical cellular organelles that stain for lipids, have no discernible internal structure, and often contain carotenoids and possibly other chemicals. A survey of 97 species of anuran amphibians (frogs and toads) revealed that all species of 16 families surveyed possessed yellow oildroplets of varying size in the cells of the pigment epithelium, except for three species that appear to have secondarily lost them during evolution. Furthermore, 25 species of six families also possess colorless oildroplets at the distal end of the inner segments of single cones and principal cones of the double-cone system; two species of the Ranidae appear to have secondarily lost such retinal oildroplets. Every species possesses epithelial or retinal oildroplets or both. Lastly, small oildroplet-like inclusions were discovered in the red blood cells of two species. All of Walls' ('42) summary generalizations about anuran oildroplets are incorrect: oildroplets are not restricted to the Ranidae, are not yellow when found in the cones, and do not correlate with photoactic behavior in 87 species. Evidence is reviewed suggesting that the primary function of anuran oildroplets is chemical storage, perhaps related to the visual pigment cycle. Oildroplets in the cones may additionally act as filters of ultraviolet radiation.
陆生脊椎动物眼睛中的油滴是球形细胞器，能被脂质染色，没有可识别的内部结构，通常含有类胡萝卜素以及可能的其他化学物质。对97种无尾两栖动物（青蛙和蟾蜍）的调查显示，在所调查的16个科的所有物种中，除了3个物种在进化过程中似乎次生地失去了它们外，色素上皮细胞中都有大小各异的黄色油滴。此外，6个科的25个物种在双锥系统的单锥和主锥内段远端也有无色油滴；蛙科的2个物种似乎次生地失去了这种视网膜油滴。每个物种都有上皮油滴或视网膜油滴或两者都有。最后，在2个物种的红细胞中发现了小的油滴状内含物。沃尔斯（1942年）关于无尾两栖动物油滴的所有总结概括都是错误的：油滴并不局限于蛙科，在视锥细胞中发现时并非黄色，并且与87个物种的光活动行为无关。有证据表明，无尾两栖动物油滴的主要功能是化学物质储存，可能与视觉色素循环有关。视锥细胞中的油滴可能还起到过滤紫外线的作用。
