The Sensory Epithelia of the Inner Ear of Two Turtles,Testudo graecaL. andPseudemys scripta(Schoepff)

Abstract

In the inner ear of Testudo graeca and Pseudemys scripta two types of hair cells are found in all sensory epithelia except for the basilar papilla. The type I hair cell is enclosed in a nerve chalice, while the type II hair cell basally receives bouton-shaped nerve endings. In the cristae anterior and posterior, the hair cells type I are situated in two areas, in one larger area in the crista horizontalis. In the macula utriculi, the type I hair cells are situated in a narrow belt, the striola, which runs close to the anterior and lateral borders. In the maculae sacculi and lagenae the type I hair cells are found in two belts which lie parallel to the long axis of the sensory epithelia. The hair cells in the maculautriculi are oriented with their kinocilia towards the striola, while in the saccular and lagenar macula they are oriented away from the striola. In the basilar papilla all hair cells are oriented posteriorly; in the cristae anterior and posterior they are oriented utriculo-fugally, but utriculo-petally in the crista horizontalis. The hair cells in the crista neglecta are predominately oriented towards the ampulla posterior.