Intrinsically photosensitive retinal ganglion cell

Overview of the retina photoreceptors. ipRGCs labelled at the top-right.

Intrinsically photosensitive retinal ganglion cells (ipRGCs), also called photosensitive retinal ganglion cells (pRGC), or melanopsin-containing retinal ganglion cells (mRGCs), are a type of neuron in the retina of the mammalian eye. The presence of an additional photoreceptor was first suspected in 1927 when mice lacking rods and cones still responded to changing light levels through pupil constriction;[1] this suggested that rods and cones are not the only light-sensitive tissue.[2] However, it was unclear whether this light sensitivity arose from an additional retinal photoreceptor or elsewhere in the body. Recent research has shown that these retinal ganglion cells, unlike other retinal ganglion cells, are intrinsically photosensitive due to the presence of melanopsin, a light-sensitive protein. Therefore, they constitute a third class of photoreceptors, in addition to rod and cone cells.[3]

  1. ^ Keeler, Clyde E. (1927). "Iris movements in blind mice". American Journal of Physiology. 81 (1): 107–112. doi:10.1152/ajplegacy.1927.81.1.107.
  2. ^ Keeler CE (October 1928). "Blind Mice". Journal of Experimental Zoology. 51 (4): 495–508. Bibcode:1928JEZ....51..495K. doi:10.1002/jez.1400510404.
  3. ^ Do MT, Yau KW (October 2010). "Intrinsically photosensitive retinal ganglion cells". Physiological Reviews. 90 (4): 1547–81. doi:10.1152/physrev.00013.2010. PMC 4374737. PMID 20959623.