Rod

Japanese: 杆体 - かんたい

Also called rods. A part of the rod photoreceptor cells in the retina of the eye; morphologically, they are small rod-like protrusions pointing outward, and functionally, they are the photosensitive areas. They contain a pigment called rhodopsin, which fades when exposed to light and restores its color when the light is blocked. They are mixed with cones in the outer layer of the retina, but in humans, rods are far more numerous. The fovea of the retina contains only cones and no rods. The ratio of the two varies depending on the animal, and nocturnal animals such as bats, mice, owls, and deep-sea fish are almost entirely rods. Rods are said to be involved in mesopic vision, while cones are involved in diurnal vision and color vision.
→Related topics Retina | Night blindness

Source : Heibonsha Encyclopedia About MyPedia Information

Japanese:

杆状体とも。目の網膜にある杆体視細胞の一部で，形態的には外方に向かう小杆状の突出部，機能的には感光部位である。中にロドプシン（視紅）という色素を含み，光が当たるとその色があせ，光をさえぎると色が回復する。網膜外層に錐体と混在するが，ヒトでは杆体のほうがはるかに多い。網膜の中心窩(か)では錐体だけで杆体はない。両者の割合は動物によって異なり，夜行性のコウモリ，ネズミ，フクロウ，深海魚などではほとんど全部が杆体である。杆体は薄明視に関与し，錐体は昼間視と色覚に関与するとされる。
→関連項目網膜｜夜盲症

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