1A) shows ‘A schematic representation of the ear and labyrinth of Rana pipiens, in frontal section’. The first figure from Wever’s ( 1973) paper in Journal of Morphology (reproduced here as Fig. Among the best known of the English-language descriptions are those of Ernest Glen Wever. The inner ear structures of ranid frogs have been the subject of detailed anatomical accounts dating back over 150 years, many of which were written in German (see, e.g. These structures deserve further attention. Although Wever identified the contact membrane of the saccule, most recent studies of frog inner ear anatomy have overlooked both this and the amphibian tegmentum vasculosum. Wever’s diagram of the inner ear of Rana retains its value for diagrammatic purposes, but it is not anatomically accurate or representative of all frogs. The basilar and lagenar recesses are conjoined in this species. Xenopus lacks a tegmentum vasculosum and a contact membrane of the saccule the Xenopus ear is further distinguished by a lateral passage separating stapes from periotic cistern and a more direct connection between periotic cistern and basilar recess. There appeared to be a complete fluid pathway between the right and left periotic labyrinths in this species, crossing the cranial cavity. These features were also identified in Eleutherodactylus, but in this tiny frog the relative proportions of the semicircular canals and saccule resemble those of ranid tadpoles.
The amphibian ‘tegmentum vasculosum’ was distinguishable as a thickened epithelial lining within a posterior recess of the superior saccular chamber. In Rana, three discrete contact membranes were found to separate the posterior otic (=endolymphatic) labyrinth from the periotic (=perilymphatic) system: those of the amphibian and basilar recesses and the contact membrane of the saccule.
Frog dissection diagram serial#
We sought to investigate to what extent this diagram is an accurate and representative depiction of the anuran inner ear, using three-dimensional reconstructions made from serial sections of Rana pipiens, Eleutherodactylus limbatus and Xenopus laevis. Many recent accounts of the frog peripheral auditory system have reproduced Wever’s ( 1973) schematic cross-section of the ear of a leopard frog.
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