The structure of the nasal chemosensory system in squamate reptiles. 2. Lubricatory capacity of the vomeronasal organ

The vomeronasal organ is a poorly understood accessory olfactory organ, pre sent in many tetrapods. In mammals, amphibians and lepidosaurian reptiles, it is an encapsulated structure with a central, fluid-filled lumen. The mor phology of the lubricatory system of the vomeronasal organ (the source of t his fluid) varies among classes, being either intrinsic (mammalian and caec ilian amphibian vomeronasal! glands) or extrinsic (anuran and urodele nasal glands). In the few squamate reptiles thus far examined, there are no subm ucosal vomeronasal glands. In this study, we examined the vomeronasal organ s of several species of Australian squamates using histological, histochemi cal and ultrastructural techniques, with the goal of determining the morpho logy of the lubricatory system in the vomeronasal organ. Histochemically, t he fluid within the vomeronasal organ of all squamates is mucoserous, thoug h it is uncertain whether mucous and serous constituents constitute separat e components. The vomeronasal organ produces few secretory granules intrins ically, implying an extrinsic source for the luminal fluid. Of three possib le candidates, the Harderian gland is the most likely extrinsic source of t his secretion.