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. 2013 Jun 7;8(6):e66480. doi: 10.1371/journal.pone.0066480

Figure 9. Schematic summary of pathways by which rod signals could reach ipRGCs.

Figure 9

The ipRGC is a hybrid of known melanopsin-expressing ganglion cell types, some of which stratify exclusively in the uppermost OFF sublayer (site 3), others in the ON sublayer (e.g., site 2), and still others in both (see text). Jagged lines represent gap junctional contacts between AII amacrine cells and ON cone bipolar terminals (site 1) and between rods and cones (site 4). The primary rod pathway is shown in red, the secondary rod pathway in green, and a novel pathway from rods to ON cone bipolar cells in blue [35]. All of these pathways have been considered to relay to ganglion cells in the ON sublayer (site2), but they may also pass through ectopic ON cone bipolar terminals in the OFF sublayer to the dendrites of some ipRGCs (site 3; see text). A pathway directly linking rod bipolar cells to ipRGCs, proposed by Ostergaard et al. (2007) [17], is shown in gold. R: rod; C: cone; RB: rod bipolar cell; CBon: ON cone bipolar cell; AII: AII amacrine cell; ipRGC: intrinsically photosensitive retinal ganglion cell. Horizontal gray lines indicate the ON and OFF sublayers of the inner plexiform layer.