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attract the growing ganglia toward the otocyst causing the neurons to enter at the
appropriate sites (Hemond and Morest 1992 ; Bianchi and Cohan 1993 ). Although
the exact timing of innervation by auditory afferents and efferents is not well studied in fi shes, nerve innervation appears to take place before functional maturation of
Fig. 3 Embryonic development of the auditory system in fi shes. ( a ) Shows epithelial thickening
in the ectoderm (ed) which is induced in ( b ) to form the auditory placode (ap) in the ectoderm of
the developing embryo. In ( c ) the auditory placode invaginates to form the otic pit (op) and the
subsequent closing of the otic pit in ( d ) forms the otocyst (o), which separates from the ectoderm.
In ( e ) the otocyst polarizes and begins to differentiate into the various endorgans of the auditory
and vestibular systems. R—rhombencephalon, M—head mesenchyme, ph—pharynx, ed—ectoderm, ap—auditory placode, op—otic pit, o—otocyst, VIII—cranial nerve VIII
Development of Structure and Sensitivity of the Fish Inner Ear
attract the growing ganglia toward the otocyst causing the neurons to enter at the
appropriate sites (Hemond and Morest 1992 ; Bianchi and Cohan 1993 ). Although
the exact timing of innervation by auditory afferents and efferents is not well studied in fi shes, nerve innervation appears to take place before functional maturation of
Fig. 3 Embryonic development of the auditory system in fi shes. ( a ) Shows epithelial thickening
in the ectoderm (ed) which is induced in ( b ) to form the auditory placode (ap) in the ectoderm of
the developing embryo. In ( c ) the auditory placode invaginates to form the otic pit (op) and the
subsequent closing of the otic pit in ( d ) forms the otocyst (o), which separates from the ectoderm.
In ( e ) the otocyst polarizes and begins to differentiate into the various endorgans of the auditory
and vestibular systems. R—rhombencephalon, M—head mesenchyme, ph—pharynx, ed—ectoderm, ap—auditory placode, op—otic pit, o—otocyst, VIII—cranial nerve VIII
Development of Structure and Sensitivity of the Fish Inner Ear