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De Vreese S, Orekhova K, Morell M, Gerussi T, Graïc JM. Neuroanatomy of the Cetacean Sensory Systems. Animals (Basel) 2023; 14:66. [PMID: 38200796 PMCID: PMC10778493 DOI: 10.3390/ani14010066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Revised: 11/10/2023] [Accepted: 12/21/2023] [Indexed: 01/12/2024] Open
Abstract
Cetaceans have undergone profound sensory adaptations in response to their aquatic environment during evolution. These adaptations are characterised by anatomo-functional changes in the classically defined sensory systems, shaping their neuroanatomy accordingly. This review offers a concise and up-to-date overview of our current understanding of the neuroanatomy associated with cetacean sensory systems. It encompasses a wide spectrum, ranging from the peripheral sensory cells responsible for detecting environmental cues, to the intricate structures within the central nervous system that process and interpret sensory information. Despite considerable progress in this field, numerous knowledge gaps persist, impeding a comprehensive and integrated understanding of their sensory adaptations, and through them, of their sensory perspective. By synthesising recent advances in neuroanatomical research, this review aims to shed light on the intricate sensory alterations that differentiate cetaceans from other mammals and allow them to thrive in the marine environment. Furthermore, it highlights pertinent knowledge gaps and invites future investigations to deepen our understanding of the complex processes in cetacean sensory ecology and anatomy, physiology and pathology in the scope of conservation biology.
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Affiliation(s)
- Steffen De Vreese
- Laboratory of Applied Bioacoustics (LAB), Universitat Politècnica de Catalunya-BarcelonaTech (UPC), 08800 Vilanova i la Geltrú, Spain
| | - Ksenia Orekhova
- Department of Comparative Biomedicine and Food Science (BCA), University of Padova, 35020 Legnaro, Italy; (K.O.); (T.G.); (J.-M.G.)
| | - Maria Morell
- Institute for Terrestrial and Aquatic Wildlife Research (ITAW), University of Veterinary Medicine Hannover, Foundation, 25761 Büsum, Germany;
| | - Tommaso Gerussi
- Department of Comparative Biomedicine and Food Science (BCA), University of Padova, 35020 Legnaro, Italy; (K.O.); (T.G.); (J.-M.G.)
| | - Jean-Marie Graïc
- Department of Comparative Biomedicine and Food Science (BCA), University of Padova, 35020 Legnaro, Italy; (K.O.); (T.G.); (J.-M.G.)
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Keenan TF, McLellan WA, Rommel SA, Costidis AM, Harms CA, Thewissen 'HJ, Rotstein DS, Gay MD, Potter CW, Taylor AR, Wang Y, Pabst DA. Gross and histological morphology of the cervical gill slit gland of the pygmy sperm whale (Kogia breviceps). Anat Rec (Hoboken) 2021; 305:688-703. [PMID: 34288509 DOI: 10.1002/ar.24707] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Accepted: 05/14/2021] [Indexed: 11/11/2022]
Abstract
Odontocete cetaceans have undergone profound modifications to their integument and sensory systems and are generally thought to lack specialized exocrine glands that in terrestrial mammals function to produce chemical signals (Thewissen & Nummela, 2008). Keenan-Bateman et al. (2016, 2018), though, introduced an enigmatic exocrine gland, associated with the false gill slit pigmentation pattern in Kogia breviceps. These authors provided a preliminary description of this cervical gill slit gland in their helminthological studies of the parasitic nematode, Crassicauda magna. This study offers the first detailed gross and histological description of this gland and reports upon key differences between immature and mature individuals. Investigation reveals it is a complex, compound tubuloalveolar gland with a well-defined duct that leads to a large, and expandable central chamber, which in turn leads to two caudally projecting diverticula. All regions of the gland contain branched tubular and alveolar secretory regions, although most are found in the caudal diverticula, where the secretory process is holocrine. The gland lies between slips of cutaneous muscle, and is innervated by lamellar corpuscles, resembling Pacinian's corpuscles, suggesting that its secretory product may be actively expressed into the environment. Mature K. breviceps display larger gland size, and increased functional activity in glandular tissues, as compared to immature individuals. These results demonstrate that the cervical gill slit gland of K. breviceps shares morphological features of the specialized, chemical signaling, exocrine glands of terrestrial members of the Cetartiodactyla.
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Affiliation(s)
- Tiffany F Keenan
- Department of Biology and Marine Biology, University of North Carolina Wilmington, Wilmington, North Carolina
| | - William A McLellan
- Department of Biology and Marine Biology, University of North Carolina Wilmington, Wilmington, North Carolina
| | - Sentiel A Rommel
- Department of Biology and Marine Biology, University of North Carolina Wilmington, Wilmington, North Carolina
| | | | - Craig A Harms
- Center for Marine Sciences and Technology, North Carolina State University, Morehead City, North Carolina
| | - 'Hans' Jgm Thewissen
- Department of Anatomy/Neurobiology, Northeast Ohio Medical University, Rootstown, Ohio
| | | | - Mark D Gay
- Department of Biology and Marine Biology, University of North Carolina Wilmington, Wilmington, North Carolina
| | - Charles W Potter
- Department of Vertebrate Zoology, Smithsonian Institution, National Museum of Natural History, Washington, District of Columbia, USA
| | - Alison R Taylor
- Department of Biology and Marine Biology, University of North Carolina Wilmington, Wilmington, North Carolina
| | - Ying Wang
- University of North Carolina Wilmington, Department of Chemistry and Biochemistry, Wilmington, North Carolina
| | - D Ann Pabst
- Department of Biology and Marine Biology, University of North Carolina Wilmington, Wilmington, North Carolina
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