The main chemosensory organs, receptors and putative ligands in the mouse and the fruit fly. The image of the mouse head was adapted from Matsunami & Amrein (2003). FPRs, formyl peptide receptors; GRs, gustatory receptors; IRs, ionotropic receptors; ORs, odorant receptors; T1Rs, taste receptors type 1; T2Rs, taste receptors type 2; TAARs, trace amine-associated receptors; V1Rs, vomeronasal receptors type 1; V2Rs, vomeronasal receptors type 2.