Dr. Matthew Mason: Further Information...
University Physiologist Tel: +44 (0)1223 333829, Fax: +44 (0)1223 333840, E-mail: mjm68@cam.ac.uk
Mason, M.J., Segenhout, J.M., Cobo-Cuan, A., Quiñones, P.M. & van Dijk, P. (2015) The frog inner ear: picture perfect? Journal of the Association for Research in Otolaryngology 16: 171-188.
The study of the inner ear of amphibians is often introduced using the classic drawing of a cross-section through the leopard frog ear, originally published by Ernest Glen Wever in 1973. This famous illustration has been reproduced many times in books, high-profile review articles and scientific papers, and we have also seen it used to illustrate undergraduate lectures. However, based on our previous studies, we had reason to question the accuracy of this illustration and we wondered to what extent it is diagrammatic, and to what extent it represents a wider range of species than the one depicted. To answer these questions, we made 3D reconstructions from serial histological sections through the ears of three species of frogs, Rana pipiens, Eleutherodactylus limbatus and Xenopus laevis, and compared these to Wever's drawing. We found that the classic drawing, although extremely useful in many respects, is inaccurate: we produced an anatomically-correct version. We also identified several enigmatic structures which have been largely neglected in recent descriptions of amphibian ears: the amphibian tegmentum vasculosum (which may produce endolymph) and the contact membrane of the saccule (which may be a window for acoustic energy to bypass the auditory papillae) are found in Rana and Eleutherodactylus, while there is a lateral passage to the inner ear in Xenopus. In Xenopus only, the basilar papilla and lagenar recess arise from the same diverticulum of the saccule, a primitive vertebrate feature which appears to have been hitherto unknown in frogs. We also found what appears to be a fluid connection between the right and left ears of E. limbatus, one of the world's smallest frogs.
Please click here to see the article on the JARO website..
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