A study of pupil in Medaka

教科书上说，大多数硬骨鱼的虹膜大小不会改变，尽管包括软骨鱼在内的所有脊椎动物都会在自主神经系统控制的强光下改变虹膜的大小。本研究采用高分辨率数字图像记录和图像分析技术，对青海硬骨鱼模型虹膜的大小变化进行了细致的研究。当暴露在强光下时，青竹缩小了瞳孔，表现出缩影。此外，给予乙酰胆碱或坦索罗辛激活副交感神经系统活动会导致虹膜缩小，强烈表明青竹虹膜是通过自主神经系统控制而收缩的，与人类的方式相同。服用阿托品或苯肾上腺素并没有增加瞳孔的大小，这表明受检者的虹膜最大可能是因为拍照完全激活了交感神经活动。

Textbooks say that the iris size does not change in most species of teleost, although all vertebrates including Chondrichthyes change the size of iris in response to strong light under control by autonomic nervous system. In this study, employing high-resolution digital image recording and image analysis the size change of iris was examined carefully in a model teleost, medaka (Oryzias latipes). When exposed to strong light, medaka decreased the size of pupil, showing miosis. Moreover, activation of parasympathetic nervous system activity by administration of acetylcholine or tamsulosin induced miosis, strongly suggesting that iris contracts via control by autonomic nervous system in medaka as the same manner as human. Administration of atropine or phenylephrine did not increase the size of pupil, suggesting that the iris of the examined individual expanded maximum presumably because sympathetic nervous activity was thoroughly activated by taking pictures.