Term: type III ganglion cell

Definition: The Type III ganglion cells resemble Type II ganglion cells in most respects. They are multipolar with 3 4 primary dendrites, a cell body 20-25 micrometers in major diameter, and a dendritic field which may be more than 1000 micrometers in diameter. They differ in that some of their dendrites extend below the cell body and their cell bodies lie in the zone of optic fibers. The axon almost invariably runs down into the deep portion of the colliculus. Type III ganglion cells tend to have fewer, but thicker, dendrites passing through the first two zones than is usual for Type II ganglion cells. The dendrites are less spiny, branch less often, but like the other types of ganglion cells, they break up into many fine branches as they approach the surface, particularly in the upper portion of the zone of horizontal cells.