Anatomical Features of the Inner Ear in Submammalian Vertebrates

Baird, Irwin L.

doi:10.1007/978-3-642-65829-7_6

Cited by 48 publications

(85 citation statements)

References 71 publications

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“…Throughout vertebrate history, the vestibular labyrinth has been relatively conservative with similar structural features being found in species ranging from fish to mammals (Baird 1974;Lewis et al 1985). One evolutionary novelty is the type I hair cell and its associated calyx ending, which are found only in reptiles, birds, and mammals (Lysakowski 1996;Lysakowski and Goldberg 2004;Wersäll and Bagger-Sjöbäck 1974).…”

Section: Introductionmentioning

confidence: 99%

Quantal and Nonquantal Transmission in Calyx-Bearing Fibers of the Turtle Posterior Crista

Holt

Chatlani

Lysakowski³

et al. 2007

Journal of Neurophysiology

107

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Intracellular recordings were made from nerve fibers in the posterior ampullary nerve near the neuroepithelium. Calyx-bearing afferents were identified by their distinctive efferent-mediated responses. Such fibers receive inputs from both type I and type II hair cells. Type II inputs are made by synapses on the outer face of the calyx ending and on the boutons of dimorphic fibers. Quantal activity, consisting of brief mEPSPs, is reduced by lowering the external concentration of Ca 2+ and blocked by the AMPA-receptor antagonist CNQX. Poisson statistics govern the timing of mEPSPs, which occur at high rates (250-2,500/s) in the absence of mechanical stimulation. Excitation produced by canal-duct indentation can increase mEPSP rates to nearly 5,000/s. As the rate increases, mEPSPs can change from a monophasic depolarization to a biphasic depolarizinghyperpolarizing sequence, both of whose components are blocked by CNQX. Blockers of voltagegated currents affect mEPSP size, which is decreased by TTX and is increased by linopirdine. mEPSP size decreases several fold after impalement. The size decrease, although it may be triggered by the depolarization occurring during impalement, persists even at hyperpolarized membrane potentials. Nonquantal transmission is indicated by shot-noise calculations and by the presence of voltage modulations after quantal activity is abolished pharmacologically. An ultrastructural study shows that inner-face inputs from type I hair cells outnumber outer-face inputs from type II hair cells by an almost 6:1 ratio.

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Section: Introductionmentioning

confidence: 99%

Quantal and Nonquantal Transmission in Calyx-Bearing Fibers of the Turtle Posterior Crista

Holt

Chatlani

Lysakowski³

et al. 2007

Journal of Neurophysiology

107

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“…They also explained that the auditory chambers have undergone extensive evolutionary modifications and that the saccule is a prominent auditory endorgan in fish but it serves a vestibular role in mammals and birds and the primary auditory endorgan in birds and mammals is the cochlea which has no known counter-part in fishes and amphibians. (Baird, 1974;Propper et al, 1992) also explained that the vertebrate inner ear is a complex labyrinth containing multiple sensory organs. The pars superior (dorsal part of the ear) is similar among all vertebrates and consists of a central utricle, with its gravity sensing macula, and the semicircular canals, whose ampullary connections to the utricle contain rotation-sensing crista.…”

Section: Discussionmentioning

confidence: 99%

“…(Fritzsch et al, 2002) explained that the number of the sensory organs involved in balance and auditory function varies across the vertebrates from thee in hag fish, six in mammals, eight in birds and frog to nine in some species of limbless amphbians. (Baird, 1974& Propper et al, 1992) also explained that the vertebrate inner ear is a complex labyrinth containing multiple sensory organs.…”

Section: Discussionmentioning

confidence: 99%

Embryonic developmental study on inner ear of Columba livia domestica (the early, intermediate stages)

EL-Balshy

El-Hady²,

El-Hady³

et al. 2014

International Journal of Biological Research

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The present study deals with the embryonic development of the early and the intermediate embryonic stages of Columba livia domestica inner ear or the membranous labyrinth (10,15,20,22,26,30,33,36 and 47 mm total body length). During the early development (10 mm stage), neuroepithelium of the ventral rhompencephalon evaginates laterally to form an ectoderm thickening, the otic placode. The latter invaginates forming the otocyst that subsequently gives all other components of the membranous labyrinth. The surrounding mesenchyme is the origin of cartilaginous capsule of the ear. The endolymphatic duct is the first appeared structure in 15 mm stage, followed by cochlear duct (in 22 mm stage) and finally the three semicircular ducts. The latter begin in 26 mm stage and end in 47 mm stage .The inner ear contains sensory organs; the macula of ( utriclus , sacculus) and the crista ampullaris ( of the three semicircular canals ) and the basilar papillae of the cochlear duct; not only for the sense of hearing but also for the equilibrium ,stability and balance. The sensory organs of the intermediate stages (36 and 47 mm stages) showed no differentiation to hair or supporting cells. In the intermediate stage (47 mm stage), the inner ear has undergone a considerable development in its structure. It consists of a dorsal vestibular part including two connecting sacs (utriculus and the sacculus) and three semicircular canals and ventral cochlear part (the cochlear duct).

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“…Separating the scala media from the scala vestibuli, this archosaur tegmentum vasculosum is believed to combine the roles of the stria vascularis and Reissner's membrane in mammals (Baird 1974;Lewis et al 1985;Hossler et al 2002). The same term has long been used in the German anatomical literature to describe the thickened layer of epithelial cells found in the superior saccule of certain frogs (e.g.…”

Section: The Tegmentum Vasculosummentioning

confidence: 99%

The Frog Inner Ear: Picture Perfect?

Mason

Segenhout

Cobo-Cuan

et al. 2015

JARO

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Many recent accounts of the frog peripheral auditory system have reproduced Wever's (1973) schematic cross-section of the ear of a leopard frog. 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. 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. The amphibian 'tegmentum vasculosum' was distinguishable as a thickened epithelial lining within a posterior recess of the superior saccular chamber. 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. There appeared to be a complete fluid pathway between the right and left periotic labyrinths in this species, crossing the cranial cavity. 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. The basilar and lagenar recesses are conjoined in this species. 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. 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. These structures deserve further attention.

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Anatomical Features of the Inner Ear in Submammalian Vertebrates

Cited by 48 publications

References 71 publications

Quantal and Nonquantal Transmission in Calyx-Bearing Fibers of the Turtle Posterior Crista

Quantal and Nonquantal Transmission in Calyx-Bearing Fibers of the Turtle Posterior Crista

Embryonic developmental study on inner ear of Columba livia domestica (the early, intermediate stages)

The Frog Inner Ear: Picture Perfect?

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