Notes on the comparative anatomy of the sensory areas of the vertebrate inner ear

Weston, Jean K.

doi:10.1002/cne.900700303

Cited by 18 publications

(12 citation statements)

References 6 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A similar condition of the ganglia is also known from birds (e.g., Boord, ; Fischer et al, ). The current consensus is that the intra‐otic position of the ganglion of the basilar papilla is typical for amniotes (Weston, ; Manley and Clack, ; Fritzsch et al, ), and possibly for all sarcopterygian vertebrates (Fritzsch et al, ). The amniotic basilar papilla is the positional homolog to the therian organ of Corti although it is histologically distinct.…”

Section: Discussionmentioning

confidence: 99%

“…Monotremes possess the organ of Corti inside the main part of the cochlea, but they also have a sensory lagenar macula at the distal end. The former is a derived feature of mammals, and the latter is a feature of all amniote vertebrates, which was lost in therian mammals (Gray, 1908;Weston, 1939;Baird, 1960;Fritzsch et al, 2013). Monotremes and therians also differ in the degree of curvature or coiling of the cochlear canal (Denker, 1901;Alexander, 1904;Luo et al, 2011), and in the presence or absence of a perilymphatic foramen (Gaupp, 1908;Kuhn, 1971;Zeller, 1989Zeller, , 1993Wible and Hopson, 1995;Rougier et al, 1996;Rougier and Wible, 2006).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Inner ear labyrinth anatomy of monotremes and implications for mammalian inner ear evolution

Schultz

Zeller

Luo

2016

Journal of Morphology

View full text Add to dashboard Cite

The monophyletic clade Monotremata branches early from the rest of the mammalian crown group in the Jurassic and members of this clade retain many ancestral mammalian traits. Thus, accurate and detailed anatomical descriptions of this group can offer unique insight into the early evolutionary history of Mammalia. In this study, we examine the inner ear anatomy of two extant monotremes, Ornithorhynchus anatinus and Tachyglossus aculeatus, with the primary goals of elucidating the ancestral mammalian ear morphology and resolving inconsistencies found within previous descriptive literature. We use histological serial sections and high-resolution microcomputed tomography (µCT) for correlating soft tissue features of the vestibule and cochlea to the osseous labyrinth endocast. We found that in both monotremes the scala tympani coils to a lesser degree than scala vestibuli and scala media, although all three scalae show an apical coil inside the osseous cochlear tube. The helicotrema (conduit between scala tympani and scala vestibuli) is in subapical position, and the cochlear and lagenar ganglia and their associated nerve fibers are not enclosed by bone. In comparison, in extant therian mammals (i.e., marsupials and placentals) the helicotrema is located at the apex of the osseous cochlear canal, the three scalae coil to the same degree and the cochlear ganglion is enclosed by the primary bony lamina. Whether the lagenar ganglion is lost in therian mammals or integrated into the cochlear ganglion is still debated. The presence of a sensory lagenar macula at the apex of the membranous cochlear duct, innervated by a separate lagenar nerve and ganglion is a plesiomorphic condition of amniotes that monotremes share. A separate osseous lagenar canaliculus for the lagenar nerve, and the coiling of the distended lagenar sac at the end of the cochlear duct are autapomorphies of monotremes. Based on our findings we hypothesize that the ancestral inner ear of stem mammaliaforms is characterized by a straight or slightly curved osseous cochlear canal, a lagenar macula, lagenar nerve fibers separated from a larger bundle of cochlear nerve fibers, the presence of an organ of Corti and an intra-otic cochlear ganglion suspended by membranous connective tissue. Among the major Mesozoic clades of crown mammals, cladotherians and gondwanatherians most likely acquired a fully functioning organ of Corti but lost the sensory lagenar macula, like extant therians. However, Mesozoic spalacotherioids, multituberculates and eutriconodonts likely retained the mammaliaform condition. J. Morphol. 278:236-263, 2017. © 2016 Wiley Periodicals,Inc.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Inner ear labyrinth anatomy of monotremes and implications for mammalian inner ear evolution

Schultz

Zeller

Luo

2016

Journal of Morphology

View full text Add to dashboard Cite

show abstract

“…It has long been known that there are wide variations in the structure of the inner ears of vertebrates (Evans, 1935;Gray, 1908;Pritchard, 1881;Retzius, 1884;Weston, 1939). Variations range from gross changes in the structure of the bony labyrinth and perilymphatic and endolymphatic ducts, to the fine structure of the basilar membrane and sensory cells (Baird, 1969;Pye, 1966a, b;Smith and Takasaka, 1971;Webster, 1966) and tectorial membrane (Wever, 1967a, b), distribution of hair cells (Smith and Takasaka, 1971;Wever, 1965) and hair cell orientation (Baird, 1969(Baird, , 1970Mulroy, 1968).…”

Section: Dimensional Changes In the Inner Earmentioning

confidence: 99%

A Review of Some Current Concepts of the Functional Evolution of the Ear in Terrestrial Vertebrates

Manley

1972

Evolution

View full text Add to dashboard Cite

“…In birds the intraotic gan glion innervates the basilar papilla and the macula lagena; all other avian sensory areas associated with the posterior ramus are innervated by the intracranial ganglion [Weston, 1939]. Relatively recent studies on the pi geon show that the cochlear and lagenar portions of the posterior ramus are intimately connected, but their cell bodies lie in either of two separate ganglia -the cochlear ganglion or the lagenar ganglion -both of which are intraotic in position.…”

Section: Posterior Ramusmentioning

confidence: 99%

“…The reptilian intraotic ganglion, the axons of which form the posterior ramus, supplies its dendritic projections to the basilar papilla, the macula lagena, and the posterior crista; some fibers separate from the posterior ramus and from branchlets to the macula neglecta and part of the macula sacculus, and the cell bodies supplying such fibers are located in the intra cranial ganglion [Weston, 1939;B aird, 1970]. In birds the intraotic gan glion innervates the basilar papilla and the macula lagena; all other avian sensory areas associated with the posterior ramus are innervated by the intracranial ganglion [Weston, 1939].…”

Section: Posterior Ramusmentioning

confidence: 99%

Projections of the Intraotic Ganglion to the Medullary Nuclei in the Tegu Lizard, <i>Tupinambis nigropunctatus</i>

DeFina¹,

Webster²

1974

Brain Behav Evol

View full text Add to dashboard Cite

The auditory and vestibular projectionsof the posterior ramus of the statoacoustic nerve were traced using silver degeneration techniques in the tegu lizard, Tupinambis nigropunctatus. Four tegus were perfused 7, 14, 21, and 28 days after labyrinthectomy, and three were perfused 21 days after cochlear ductectomy; 21 days was found to provide optimal degeneration patterns. Both surgical procedures destroyed the intraotic ganglion of the posterior ramus, which innervates the posterior crista, basilar papilla, macula lagena, macula sacculus, and possibly the macula neglecta. The vestibular components of the posterior ramus project to the medioventral part of the dorsolateral nucleus, the dorsal and dorsomedial parts of the ventrolateral nucleus, the dorsal part of the descending nucleus, and throughout the dorsomedial nucleus. No direct vestibulocerebellar tract is associated with the intraotic ganglion. The auditory components of the posterior ramus project to the entire nucleus angularis and nucleus magnocellularis. The nucleus laminaris receives either no primary statoacoustic fibers or very sparse projections on its lateral border.

show abstract

Notes on the comparative anatomy of the sensory areas of the vertebrate inner ear

Abstract: Froni thr Anutonitccrl 1natitsi:r of 1Wr Rq;3s-Tnivrrsrtr t t te Groningen, Hollaud.)

Cited by 18 publications

References 6 publications

Inner ear labyrinth anatomy of monotremes and implications for mammalian inner ear evolution

Inner ear labyrinth anatomy of monotremes and implications for mammalian inner ear evolution

A Review of Some Current Concepts of the Functional Evolution of the Ear in Terrestrial Vertebrates

Projections of the Intraotic Ganglion to the Medullary Nuclei in the Tegu Lizard, <i>Tupinambis nigropunctatus</i>

Contact Info

Product

Resources

About