retinal rod

retinal rod
one of the two types of visual cells, along with retinal cones, having synapses internally with bipolar retinal cells. Rods serve night vision and detection of motion. Their synaptic terminals are spherical, and their dendritic inner and outer segments are long and cylindrical. Rods have membranous disks, free saccules that contain rhodopsin and are completely enclosed by the outer cell membrane. There are about 120 million rods in the retina. None are in the foveola; the greatest concentration is about 20 degrees away from the fovea centralis, and the density gradually decreases approaching the periphery of the retina. Called also rod and rod cell.

Medical dictionary. 2011.

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Look at other dictionaries:

  • retinal rod — noun a visual receptor cell that is sensitive to dim light • Syn: ↑rod, ↑rod cell • Hypernyms: ↑visual cell • Part Holonyms: ↑retina • Part Meronyms: ↑ …   Useful english dictionary

  • retinal rod — Major photoreceptor cell of vertebrate retina (about 125 million in a human eye). Columnar cells (about 40 m m long, 1 m m diameter) having three distinct regions: a region adjacent to, and synapsed with, the neural layer of the retina contains… …   Dictionary of molecular biology

  • retinal purple — noun a red photopigment in the retinal rods of vertebrates; dissociates into retinene by light • Syn: ↑visual purple, ↑rhodopsin • Hypernyms: ↑photopigment • Part Holonyms: ↑rod, ↑rod cell, ↑ …   Useful english dictionary

  • rod cell — noun a visual receptor cell that is sensitive to dim light • Syn: ↑rod, ↑retinal rod • Hypernyms: ↑visual cell • Part Holonyms: ↑retina • Part Meronyms: ↑ …   Useful english dictionary

  • rod cell — See retinal rod …   Dictionary of molecular biology

  • rod outer segment — See retinal rod …   Dictionary of molecular biology

  • rod fiber — a fiberlike extension of a retinal rod, running from the inner segment of the dendrite to the nucleus to the spherule …   Medical dictionary

  • rod spherule — the pear shaped ending of a retinal rod cell, which synapses with the bipolar and horizontal cells in the outer plexiform layer …   Medical dictionary

  • rod fiber — noun : the terminal fiber of a retinal rod …   Useful english dictionary

  • rod granule — noun : the cell body of a retinal rod …   Useful english dictionary

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