Biplexiform cells: ganglion cells of the primate retina that contact photoreceptors.

Golgi-impregnated biplexiform cells of the macaque retina are neurons with cell bodies in the ganglion cell layer, an axon in the nerve fiber layer, and dendrites in the inner plexiform layer that are postsynaptic to amacrine cell processes and bipolar cell axon terminals. In these features they resemble conventional ganglion cells, but they also have processes that arise from the main dendritic arborization, extend to the outer plexiform layer, and are postsynaptic to rod photoreceptor terminals as central elements at the ribbon synaptic complex. However, ordinary retinal ganglion cell dendrites ramify in the inner plexifrom layer and do not contact photoreceptors. Thus, biplexiform cells represent a previously undescribed class of neuron, part of whose synaptic input could bypass the commonly described interneuron circuitry of the vertebrate retina.