Morphology of vertebrate cone and rod photoreceptors. Each includes an inner
segment and an outer segment connected by a cilium. The inner segment contains
the cell's biosynthetic machinery. Phototransduction takes place in the outer
segment. In the rods, the outer segment contains free-floating membrane-bound
disks. In cones, the disks remain continuous with the plasma membrane. Modified
from Perkins BD, Fadool JM (2010) “Photoreceptor structure and
development analyses using GFP transgenes.” Methods in Cell Biology 100:
205–218, copyright 2010, with permission from Elsevier.