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Article

Selective Inner Hair Cell Loss in a Neonate Harbor Seal (Phoca vitulina)

1
Institute for Terrestrial and Aquatic Wildlife Research, University of Veterinary Medicine Hannover, Foundation, 25761 Büsum, Germany
2
Zoology Department, The University of British Columbia, Vancouver, BC V6T 1Z4, Canada
3
Faculty of Veterinary Medicine and Zootechnics, National Autonomous University of Mexico, Av. Universidad 3000, Delegación Coyoacán, Mexico City 04510, Mexico
4
Vancouver Aquarium Marine Science Center, Vancouver, BC V6G 3E2, Canada
5
Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, 22529 Hamburg, Germany
6
Animal Health Center, Ministry of Agriculture, Abbotsford, BC V3G 2M3, Canada
*
Author to whom correspondence should be addressed.
Academic Editor: Catarina Eira
Animals 2022, 12(2), 180; https://doi.org/10.3390/ani12020180
Received: 22 December 2021 / Revised: 6 January 2022 / Accepted: 7 January 2022 / Published: 12 January 2022
(This article belongs to the Special Issue Pathology of Marine Mammals)
Congenital hearing loss (i.e., hearing impairment present at birth) is recognized in humans and other terrestrial species, but there is a lack of information on congenital malformations and associated hearing loss in pinnipeds (seals, sea lions, and walruses). Baseline knowledge on marine mammal inner ear malformations is essential to differentiate between congenital and acquired abnormalities, which may be caused by infectious agents, age, or anthropogenic interactions, such as noise exposure. Analysis of the cochlea of a neonate harbor seal (Phoca vitulina) revealed bilateral loss of inner hair cells (sensory cells responsible for transducing the auditory signal) while the outer hair cells (sensory cells responsible for sound amplification and frequency selectivity and sensitivity) were intact. The selective inner hair cell loss (up to 84.6% of loss) was more severe in the basal turn, where the high frequencies are encoded. Potential causes and consequences are discussed. This is the first report of a case of selective inner hair cell loss in a marine mammal neonate, likely congenital.
Congenital hearing loss is recognized in humans and other terrestrial species. However, there is a lack of information on its prevalence or pathophysiology in pinnipeds. It is important to have baseline knowledge on marine mammal malformations in the inner ear, to differentiate between congenital and acquired abnormalities, which may be caused by infectious pathogens, age, or anthropogenic interactions, such as noise exposure. Ultrastructural evaluation of the cochlea of a neonate harbor seal (Phoca vitulina) by scanning electron microscopy revealed bilateral loss of inner hair cells with intact outer hair cells. The selective inner hair cell loss was more severe in the basal turn, where high-frequency sounds are encoded. The loss of inner hair cells started around 40% away from the apex or tip of the spiral, reaching a maximum loss of 84.6% of hair cells at 80–85% of the length from the apex. Potential etiologies and consequences are discussed. This is believed to be the first case report of selective inner hair cell loss in a marine mammal neonate, likely congenital. View Full-Text
Keywords: congenital hearing loss; organ of Corti; marine mammals; pinnipeds; scanning electron microscopy; hair cell loss congenital hearing loss; organ of Corti; marine mammals; pinnipeds; scanning electron microscopy; hair cell loss
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MDPI and ACS Style

Morell, M.; Rojas, L.; Haulena, M.; Busse, B.; Siebert, U.; Shadwick, R.E.; Raverty, S.A. Selective Inner Hair Cell Loss in a Neonate Harbor Seal (Phoca vitulina). Animals 2022, 12, 180. https://doi.org/10.3390/ani12020180

AMA Style

Morell M, Rojas L, Haulena M, Busse B, Siebert U, Shadwick RE, Raverty SA. Selective Inner Hair Cell Loss in a Neonate Harbor Seal (Phoca vitulina). Animals. 2022; 12(2):180. https://doi.org/10.3390/ani12020180

Chicago/Turabian Style

Morell, Maria, Laura Rojas, Martin Haulena, Björn Busse, Ursula Siebert, Robert E. Shadwick, and Stephen A. Raverty. 2022. "Selective Inner Hair Cell Loss in a Neonate Harbor Seal (Phoca vitulina)" Animals 12, no. 2: 180. https://doi.org/10.3390/ani12020180

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