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The vomeronasal organ allows detection of pheromones from other individuals of the same species; it is found in many animals, including man, though it may not function in the latter. In the mouse, the vomeronasal organ is a tubular structure located at the base of the nasal cavity within the nasal septum and surrounded by a bony capsule. The lumen of the vomeronasal organ is lined by pseudostratified vomeronasal neuroepithelium, consisting of receptor cells (bipolar neurons), supporting cells, and basal cells. Vomeronasal neuroepithelium is characterized by the presence of blood vessels. Vomeronasal neurons have microvilli (as opposed to the cilia found on neurons of the olfactory epithelium in the turbinate), and their axons bundle together to form the vomeronasal (Jacobson’s) nerves, which project to the accessory olfactory bulbs located dorsal and medial to the (main) olfactory bulbs. The vomeronasal organs, vomeronasal nerves, and accessory olfactory bulbs make up the accessory olfactory system, which is distinct from the main olfactory system, comprising the olfactory epithelium, olfactory nerves, and olfactory bulbs.
The 4X micrograph is a transversal section of a decalcified head, showing the nasal cavity, the nasal septum bone, and the vomeronasal organs on both sides of the nasal septum bone. The 10X and 20X micrographs exhibit, in increasing detail, the pseudostratified respiratory epithelium (with basal nuclei) of the nasal cavity and the pseudostratified neuroepithelium of the vomeronasal organ. The nerve fibers of the vomeronasal nerve are visible in the 20X and 40X micrographs. The 40X micrograph also displays the cells present in the vomeronasal neuroepithelium.
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