(A) Epithelial cells are polarized into distinct outward-facing (apical, orange) and inward-facing (basolateral, purple) surface compartments separated by tight and adherens junctions (red), while (B) most neurons are polarized into somato-dendritic (green) and axonal (blue) compartments. (C) Sensory neurons that cross an epithelium can exhibit apical-basal and axon-dendrite polarity simultaneously. (D) Olfactory receptor neurons protrude through an epithelium formed by glial-like sustentacular cells, with a dendritic knob and sensory cilia on the apical surface. (E) Photoreceptor cells protrude through an epithelium formed by Müller glia, with their apical domain (inner segment) and sensory cilium (outer segment) on the apical surface.