axon synapses in cone retinal bipolar cell type 9 cone bipolar cell (sensu Mus) An ON-bipolar neuron found in the retina and having connections with cone photoreceptors cells and neurons in the inner half of the inner plexiform layer. The dendritic tree is wide and the dendritic convergence indicates cone selectivity. The axon terminal is sparsely branched and terminates in sublamina 5 of the inner plexiform layer. BB cone bipolar cell sublaminar layer S5