Gross and histological morphology of the cervical gill slit gland of the pygmy sperm whale (Kogia breviceps).

Gross and histological morphology of the cervical gill slit gland of the pygmy sperm whale (Kogia breviceps).

Keenan TF; McLellan WA; Rommel SA; Costidis AM; Harms CA; Thewissen JGM; Rotstein DS; Gay MD; Potter CW; Taylor AR; Wang Y; Pabst DA

Anatomical Record

2021

2021-07-20

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. (© 2021 American Association for Anatomy.)

cetacean; gland; chemical communication; integument; semiochemical; CHEMICAL COMMUNICATION; PACINIAN CORPUSCLES; SIGNALS; SKIN GLANDS

Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).

journalArticle

1932-8494

NEOMED College of Medicine

Department of Anatomy & Neurobiology

August 2021 List