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Further serial transmission electron microscopy studies of auditory hair cell innervation in lizards and in a snake

1990; Wiley; Volume: 188; Issue: 2 Linguagem: Inglês

10.1002/aja.1001880207

1553-0795

Malcolm R. Miller, J Beck,

Hearing, Cochlea, Tinnitus, Genetics

Abstract Auditory hair cells of three lizard and one snake species were studied by serial transmission electron microscopy (TEM) sections of two unidirectinal hair cells (UHC) and two bidirectional hair cells (BHC) and by nonserial section montages of each entire papilla cut at 2‐μm intervals across the papillar width. The unidirectional hair cell region of the agamid lizard, Acanthosaura crucigera , lacked efferent innervation. Another agamid lizard, Agama agama , studied by nonserial section only, lacked efferent innervation to the UHC. Afferent innervation to both the UHC and BHC of Acanthosaura was primarily exclusive (each nerve fiber innervates only one hair cell), although an occasional nerve fiber innervated two hair cells. Both the UHC and the BHC of the anguid, Celestus costatus , were exclusively innervated. Both hair cell types of the varanid, Varanus exanthematicus , were nonexclusively innervated (all afferent nerve fibers innervate two or more hair cells). The auditory papilla of the colubrid snake, Elaphe obsoleta , has only one type of hair cell and each is nonexclusively innervated. The numbers of afferent and efferent nerve fibers and of afferent synapses are presented in tabular form.