Whale tear glands in the bowhead and the beluga whales: Source and function

Title

Whale tear glands in the bowhead and the beluga whales: Source and function

Creator

Rehorek Susan J; Stimmelmayr Rapahela; George John C; Suydam Robert; McBurney Denise M; Thewissen J G M

Publisher

Journal of Morphology

Date

2020
2020-03

Description

Orbital glands are found in many tetrapod vertebrates, and are usually separate structures, consisting of individual glands lying in the eyelids and both canthi of the orbit. In cetaceans, however, the orbital glandular units are less distinct and have been described by numerous authors as a single, periorbital mass. There are few histochemical and immunhistochemical studies to date of these structures. In this study, we examined the orbital glandular region of both the bowhead whale (Balaena mysticetus: Mysticeti) and the beluga whale (Delphinapterus leucas: Odontoceti) using histological, histochemical, and immunohistochemical techniques. Histologically, in the bowhead, three glandular areas were noted (circumorbital, including Harderian and lacrimal poles), palpebral (midway in the lower eyelid), and rim (near the edge of the eyelid). In the beluga, there was only a large, continuous mass within the eyelid itself. Histochemical investigation suggests neither sexual dimorphism nor age-related differences, but both whales had two cell types freely intermingling with each other in all glandular masses. Large cells (cell type 1) were distended by four histochemically distinct intracellular secretory granules. Smaller cells (cell type 2) were not distended (fewer granules) and had two to three histochemically distinct intracellular secretory granules. The beluga orbital glands had additional lipid granules in cell type 1. Counterintuitively, both lipocalin and transferrin were localized to cell type 2 only. This intermingling of cell types is unusual for vertebrates in whom individual orbital glands usually have one cell type with one to two different secretory granules present. The heterogeneity of the orbital fluid produced by cetacean orbital glands implies a complex function, or series of functions, for these orbital glands and their role in producing the tear fluid.

Subject

dolphin tursiops-truncatus; fluid; glands; harderian-gland; lacrimal gland; lactoferrin; lipocalin; localization; morphology; ocular glands; orbital whales; pacinian corpuscles; secretions

Identifier

Rights

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

Format

journalArticle

Search for Full-text

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Pages

316-325

Issue

3

Volume

281

ISSN

0362-2525

NEOMED College

NEOMED College of Medicine

NEOMED Department

Department of Anatomy & Neurobiology

Update Year & Number

June 2020 Update I

Citation

Rehorek Susan J; Stimmelmayr Rapahela; George John C; Suydam Robert; McBurney Denise M; Thewissen J G M, “Whale tear glands in the bowhead and the beluga whales: Source and function,” NEOMED Bibliography Database, accessed July 23, 2021, https://neomed.omeka.net/items/show/11028.

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