The fine structure of the olfactory and vomeronasal organs of a lizard (Tiliqua scincoides scincoides).

Olfactory epithelium in Tiliqua scinoides is of a loosely packed pseudostratified type. It receives secretion from the supporting cells and the underlying glands of Bowman. Its surface bears microvilli and cilia from sensory cells and microvilli from supporting cells. The vomeronasal epithelium is also pseudostratified but higher and more closely packed. Its surface carries microville from sensory and supporting cells but lacks cilia. Vascular connective tissue penetrates it almost to the epithelial surface but is always outlined by basal cell processes and a basal lamina. There are no secretory cells in or under the sensory epithelium but some cells in the epithelium of the mushroom body contain secretion granules. Sensory cells of both epithelia are bipolar neurons. The perikarya of the vomeronasal cells are more neuronal in character. Axonic processes are similar in both, dendrites are distinctive. Olfactory dendrites end in rounded rods bearing microvilli and cilia of an unusual type. Microville with filamentous cores occur on vomeronasal dendrites. There are no cilia, but 2-6 centrioles appear below the cell surface. Basal cells are structurally similar in both epithelia, but axonic processes of olfactory cells are surrounded by supporting cell processes, while vomeronasal axonic processes are surrounded by basal cells before they leave the epithelium. The presence of cilia and microville on the surface of the sensory cells is discussed in relation to the physical conditions surrounding them.