Functional Anatomy of the Lateral Nasal Gland in Anuran Amphibians and Its Relation to the Vomeronasal Organ

Abstract

Abstract Anuran amphibians feature at least two olfactory systems, the main olfactory organ and the vomeronasal organ (VNO). Although the main olfactory organ is known to detect air-borne olfactory stimuli, the capacities of the anuran VNO are still under discussion. One unresolved question is how chemical stimuli reach the vomeronasal sensory epithelium. The present study investigates, for the first time, the anatomical relationship between the anuran lateral nasal glands (LNG) and the VNOs of adult and developing animals. Based on the histological results, it seems very likely that the LNG is involved in the functioning of the vomeronasal system. First, the orifice of the LNG in adult animals of three investigated anuran species is always located nearby the external naris but, at the same time directly above the entrance to the lower nasal cavities and, thus, the VNO. Secretions discharged by the gland are observed to move toward this entrance. Furthermore in the development of the gland during metamorp...