Ultrastructural analysis of odontocete cochlea

dc.contributor
Universitat Politècnica de Catalunya. Departament d'Enginyeria Hidràulica, Marítima i Ambiental
dc.contributor.author
Morell Ybarz, Maria
dc.date.accessioned
2013-11-06T11:24:34Z
dc.date.available
2013-11-06T11:24:34Z
dc.date.issued
2012-05-04
dc.identifier.uri
http://hdl.handle.net/10803/125113
dc.description.abstract
The morphological study of the Odontocete organ of Corti including possible pathological features resulting from sound over-exposure, represent a key conservation issue to assess the effects of acoustic pollution on marine ecosystems. Through the collaboration with stranding networks belonging to 26 countries, 150 ears from 13 species of Odontocetes were processed. In this dissertation, we present a standard protocol to 1) compare the ultrastructure of the cochlea in several Odontocete species and 2) investigate possible damage as a consequence of sound exposure, using scanning (SEM) and transmission (TEM) electron microscopy, and immunohistochemistry. In a preliminary study, computerized tomography scans were performed before decalcification with ears of 15 odontocete species, proposing a set of standard measurements which classified very well the species. In addition, the constant ratio between measurements of inner and middle ear structures contributed to confirm the active role of the odontocete middle ear in sound reception mechanism. We established a decalcification protocol using the fast commercial decalcifier RDO® and EDTA (Ethylendiaminetetraacetic acid). Although further experiments should be conducted to assess the suitability of using one or the other method (because the number of samples treated with EDTA was comparatively small), RDO® at specific dilutions decreased the decalcification time of cetacean ear bones with control of the decalcification endpoint, helping a faster access to inner structures. The complementary use of electron microscopy and immunofluorescence allowed the description in odontocetes of new morphological features of tectorial membrane, spiral limbus, spiral ligament, stria vascularis, hair cells and their innervation. Furthermore, this study revealed qualitative and quantitative morphological characteristics of the organ of Corti in high-frequency hearing species, including 1) an outer hair cell (OHC) small length, 2) a thick cuticular plate in OHC, and a thick reticular lamina, 3) robust cup formation of the Deiters cell body, 4) the high development of cytoskeleton in Deiters and pillar cells and 5) the basilar membrane high stiffness. Interestingly, all these features, including a common molecular design of prestin, are also shared by echolocating bats, suggesting a convergent evolution in echolocating species. The presence of scars among hair cell rows, the pattern of stereocilia imprints in the tectorial membrane and the condition of fibrocytes II and IV were criteria suitable to determine or discard possible acoustic trauma, despite the numerous artefacts that rapidly develop as a consequence of tissue autolysis. Consequently, matching the preliminary approximation of the cochlear frequency map with the damaged region would bring information on the sound source that would have triggered a possible lesion.
dc.format.extent
180 p.
dc.format.mimetype
application/pdf
dc.language.iso
eng
dc.publisher
Universitat Politècnica de Catalunya
dc.rights.license
L'accés als continguts d'aquesta tesi queda condicionat a l'acceptació de les condicions d'ús establertes per la següent llicència Creative Commons: http://creativecommons.org/licenses/by/3.0/es/
dc.rights.uri
http://creativecommons.org/licenses/by/3.0/es/
*
dc.source
TDX (Tesis Doctorals en Xarxa)
dc.title
Ultrastructural analysis of odontocete cochlea
dc.type
info:eu-repo/semantics/doctoralThesis
dc.type
info:eu-repo/semantics/publishedVersion
dc.subject.udc
619
dc.subject.udc
68
dc.contributor.director
André, Michel
dc.contributor.codirector
Lenoir, Marc
dc.embargo.terms
cap
dc.rights.accessLevel
info:eu-repo/semantics/openAccess
dc.identifier.dl
B. 28130-2013


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