Vomeronasal Organ - Structure

Structure

The VNO is found at the base of the nasal cavity. It is split into two, being divided by the nasal septum, with both sides possessing an elongated c-shaped, or crescent, lumen. It is encompassed inside a bony or cartilaginous capsule which opens into the base of the nasal cavity. The vomeronasal receptor neurons possess axons which travel from the VNO to the accessory olfactory bulb (AOB) or, as its also known, the vomeronasal bulb. These sensory receptors are located on the medial concave surface of the crescent lumen. The lateral, convex surface of the lumen is covered with non sensory ciliated cells, where the basal cells are also found. At the dorsal and ventral aspect of the lumen are vomeronasal glands, which fill the vomeronasal lumen with fluid. Sitting next to the lumen are blood vessels that dilate or constrict, forming a vascular pump that deliver stimuli to the lumen. A thin duct, which opens onto the floor of the nasal cavity inside the nostril, is the only way of access for stimulus chemicals.

During embryological development, the vomeronasal sensory neurons form from the nasal (olfactory) placode, at the anterior edge of the neural plate (cranial nerve zero).