Neurons that have two cytoplasmic extensions attached to their cell body are structurally classified as bipolar. One process serves as the axon and the other the dendrite. Both processes can have many smaller branches. Bipolar neurons are found in the retina of the eye, roof of the nasal cavity, and inner ear. They are always sensory and carry information about vision, olfaction, equilibrium, and hearing. In the eye, bipolar neurons form the middle layer of the retina. Here they transfer signals from photoreceptors (= rods and cones) to ganglion cells, which carry the visual information to the brain via the optic nerve. The bipolar neurons in the nasal cavity are embedded in the olfactory mucosa, where they serve as receptors. When odorants are drawn into the nasal cavity, they bind to cilia that extend from the dendritic ends of the receptors. Action potentials are produced and carried by the receptors to the olfactory bulbs. From here, other neurons carry the olfactory information into brain for further processing. In the inner ear, bipolar neurons make up the vestibular and cochlear branches of the vestibulocochlear nerve (= cranial nerve VIII). The vestibular branch carries information into the brain about equilibrium and the cochlear branch carries information about hearing.