Journal article

Authors list: McDonald, M.; Vapniarsky-Arzi, N.; Verstraete, F. J. M.; Staszyk, C.; Leale, D. M.; Woolard, K. D.; Arzi, B.

Publication year: 2015

Pages: 582-592

Journal: Archives of Oral Biology

Volume number: 60

Issue number: 4

ISSN: 0003-9969

eISSN: 1879-1506

DOI Link: https://doi.org/10.1016/j.archoralbio.2015.01.005

Publisher: Elsevier

Abstract: 

Objectives: The temporomandibular joint (TM)) in cetaceans is largely uncharacterized. This study aims to describe the macroscopic, microscopic, biochemical and biomechanical features of the TM) of two species of the suborder Odontoceti: the harbour porpoise (Phocoena Grampus griseus). Furthermore, we aim to elucidate the structure-function relationship of their TMJs and their possible role in echolocation.

Design: The TMJs from fresh cadaver heads of harbour porpoise (n = 4) and Risso's dolphin (n = 2) acquired from stranding were examined. Following macroscopical evaluation, the TMJs were investigated for their histological, mechanical and biochemical properties.

Results: The TMJs of the studied odontocetes were found to be fundamentally different from other mammals. Macroscopically, the TMJ lacks the typical joint cavity found in most mammals and is essentially a syndesmosis. Histological and microstructural analysis revealed that the TMJ discs were composed of haphazardly intersecting fibrous-connective tissue bundles separated by adipose tissue globules and various calibre blood vessels and nerve fibres. The collagen fibre composition was primarily collagen type I with lesser amounts of collagen type II. Sulphated glycosaminoglycan (sGAG) content was lower compared to other studied mammals. Finally, mechanical testing demonstrated the disc was stronger and stiffer in the dorsoventral direction than in the mediolateral direction.

Conclusion: The spatial position of the TMJ, the absence of an articulating synovial joint, and the properties of the TM) discs all reflect the unique suction-feeding mechanism adopted by the harbour porpoise and Risso's dolphin for underwater foraging. In addition, the presence of unique adipose globules, blood vessels and nerves throughout the discs may indicate a functional need beyond food apprehension. Instead, the disc may play a role in neurological sensory functions such as echolocation. (C) 2015 Elsevier Ltd. All rights reserved.

Harvard Citation style: McDonald, M., Vapniarsky-Arzi, N., Verstraete, F., Staszyk, C., Leale, D., Woolard, K., et al. (2015) Characterization of the temporomandibular joint of the harbour porpoise (Phocoena phocoena) and Risso's dolphin (Grampus griseus), Archives of oral biology, 60(4), pp. 582-592. https://doi.org/10.1016/j.archoralbio.2015.01.005

APA Citation style: McDonald, M., Vapniarsky-Arzi, N., Verstraete, F., Staszyk, C., Leale, D., Woolard, K., & Arzi, B. (2015). Characterization of the temporomandibular joint of the harbour porpoise (Phocoena phocoena) and Risso's dolphin (Grampus griseus). Archives of oral biology. 60(4), 582-592. https://doi.org/10.1016/j.archoralbio.2015.01.005