retinal rod


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 the nucleus and other cytoplasmic organelles, below this is the inner segment, rich in mitochondria, that is connected through a thin ‘neck’ (in which is located a ciliary body) to the outer segment. The outer segment largely consists of a stack of discs (membrane infoldings that are incompletely separated in cones) that are continually replenished near the inner segment and that are shed from the distal end and phagocytosed by the pigmented epithelium. The membranes of the discs are rich in rhodopsin, the pigment that absorbs light.

Dictionary of molecular biology. 2004.

Look at other dictionaries:

  • 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… …   Medical dictionary

  • 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 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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