Freeze-fracturing of the auditory basilar papilla in the lizard Calotes versicolor.

Membrane-associated structures were studied in the cells of the basilar papilla, the hearing organ of a lizard, Calotes versicolor, by means of freeze-fracture. Zonulae occludents of an intermediate to tight type were found to join the apical membranes of sensory and supporting cells. Gap junctions were frequently observed between neighboring supporting cells. The size and shape of the gap junctions varied considerably. Their distribution was as follows: small junctions were seen apically, large ones basally. This finding suggests the existence of electrical coupling among the supporting cells. Only afferent synapses have been described in this organ. Aggregates of particles were found in the pre- as well as the post-synaptic membranes, similar to those described at synapses in the central nervous system.