Scanning electron microscope studies of some lizard basilar papillae

The papillae basilares of eight species of lizards representing four different families were studied by scanning electron microscopy. The papilla of Eublepharis macularius (Gekkota; Eublepharidae) has a midaxial area devoid of hair cells separating anterior and posterior groups of hair cells, two types of tectorial membrane modifications, bidirectionality of each of the anterior and posterior groups of ventral hair cells, and unidirectionality of the dorsal hair cells. The papilla of Coleonyx variegatus (Gekkota; Eublepharidae) is essentially similar to that of Eublepharis, but shows anterior displacement of the axial hiatus and a considerable decrease in the number of hair cells in the dorsal part of the postaxial region. The papilla of Ameiva ameiva (Teiidae) has a dorsal enlargement almost constricted from the remaining portion of the papilla and the greater number (87%) of the hair cells oriented posteriorly. Tupinambis teguixin (Teiidae) exhibits multidirectional hair cell orientation in the expanded dorsal area, bidirectionality in the narrower central segment, and unidirectionality toward the ventral end of the papilla. Gerrhonotus multicarinatus (Anguidae) shows a ventral expansion covered by a thick tectorial plate overlying short‐ciliated unidirectionally oriented hair cells and a longer dorsal segment with long‐ciliated bidirectionally oriented hair cells. The papillae of Iguana iguana, Crotaphytus collaris, and Basiliscus basiliscus (Iguanidea) have middle segments of short‐ciliated hair cells covered by a specialized tectorial plate and dorsal and ventral segments consisting of longciliated bidirectionally oriented hair cells. Basiliscus is divergent in lacking a part of the ventral long‐ciliated hair cell segment.