31. Like all monitors, the Argus has a forked tongue and a vomeronasal organ in the roof of its mouth. 32. This protein family includes metabotropic glutamate receptors, the extracellular calcium-sensing receptors, the vomeronasal type-2 receptors 33. Correspondingly, the reduction of vomeronasal receptor genes is often attributed to the transition of tetrapods from water to land. 34. Scientists have long wondered whether human behavior, too, is influenced by pheromones, because people possess a vomeronasal organ. 35. The vomeronasal organ is mainly used to detect pheromones, chemical messengers that carry information between individuals of the same species. 36. The vomeronasal organ and the main olfactory epithelium, together called the olfactory system, detect pheromones from the opposite sex. 37. Three distinct families of putative pheromone receptors have been identified in the vomeronasal organ ( V1Rs, V2Rs and V3Rs ). 38. Except the hartebeest and the topi, all bovids can detect estrus in females by testing the urine using the vomeronasal organ. 39. Chemical communication does appear to occur among humans, but this does not necessarily imply that the human vomeronasal organ is functional. 40. The vomeronasal organ s sensory neurons act on a different signaling pathway than that of the main olfactory system s sensory neurons.
