Morphological aspects of the vomeronasal organ in the lizard Tupinambis merianae

Abstract

The vomeronasal organ (VNO) is a sensory structure present in most terrestrial vertebrates, involved in the detection of pheromones associated with social and reproductive behaviors. This paper describes morphological aspects of the VNO and associated ducts in the lizard Tupinambis merianae. For their study, specimens of both sexes and various ages were anesthetized and euthanized. The organ samples were fixed in situ by perfusion or ex situ after dissection. They were then decalcified and processed according to conventional techniques for anatomical, histological and scanning electron microscopy studies. The VNO of Tupinambis merianae exhibits a typical morphological pattern, consisting of a well-developed sensory neuroepithelium and a respiratory-type non-sensory epithelium. It connects via the vomeronasal nerves with a conspicuous accessory olfactory bulb. At the base of the organ, the mouths of the Harder glands and of the vomeronasal ducts that connect with the oral cavity are placed. The second supralabial scales constitute an useful topographical reference for the VNO location. The considerable development of the VNO appears linked to the wide range of reproductive behavior in this species.