Figure 1. The two types of horizontal cell in Golgi-impregnated cat retina

Camera lucida drawings from Fisher and Boycott [1] of the two types of horizontal cell in Golgi-impregnated cat retina [2]. The dendrites of both the axonless A-type (HA) and the axon-bearing B-type (HB) contact cones only while the axon terminal system of the B-type (HBat) innervates rods exclusively [12]. Although these structures appear planar, they are not. The large dendritic and axon telodendrial trunks lie at the inner border of the outer plexiform layer (OPL) while the dendrites innervating both types of photoreceptor ramify at its outer border.