Morell, M., Lenoir, M., Puel, J., Jauniaux, T., Dabin, W., Ferreira, M., André, M. Scanning Electron Microscopy Images of Odontocete Cochlea Marine Mammal Morphology Workshop. Conference of the European Cetacean Society, Stralsund, Germany, Mar 2010 Résumé: The morphological study of the organ of Corti as well as possible alterations associated to sound exposure represent a key conservation issue to assess the effects of acoustic pollution on marine ecosystems. In addition, since odontocetes produce species-specific acoustic signals at diverse frequency ranges, differences in echolocation signals could reflect morphological differences in the cochlea. Through the collaboration of stranding networks and rehabilitation centers from several European countries that provided fresh ear samples that followed an extraction and fixation protocol (defined at the Necropsy Workshop 2009 in Liège, Belgium), scanning electron microscopy images of several cochlea structures could be obtained: e.g. hair cells and outer hair cells (OHC) stereocilia imprints in the tectorial membrane of Delphinus delphis, Phocoena phocoena and Stenella coeruleoalba. Despite the autolysis process of the organ of Corti hair cells is very fast after death, we show here that the tectorial membrane structure remains longer in acceptable conditions for analysis than the rest of the organ if fixed at least before 20h postmortem. This may allow insights of possible alterations on the OHC stereocilia by analysing their imprints on the tectorial membrane. Projet: eCREM, Effects and Control of Anthropogenic Noise in Marine Ecosystems