Passive restriction of blood flow and counter-current heat exchange via lingual retia in the tongue of a neonatal gray whale Eschrichtius robustus (Cetacea, Mysticeti).
Retia mirabilia play broad roles in cetacean physiology, including thermoregulation during feeding and pressure regulations during diving. Vascular bundles of lingual retia are described within the base of the tongue of a neonatal female gray whale (Eschrichtius robustus). Each rete consists of a central artery surrounded by four to six smaller veins. The retia and constituent vessels decrease in diameter as they extend anteriorly within the hyoglossus muscle from a position anterior to the basihyal cartilage toward the apex of the tongue. The position of the retia embedded in the hyoglossus and the anterior constriction of the vessels differs from reports of similar vascular bundles that were previously identified in gray whales. The retia likely serve as a counter-current heat exchange system to control body temperature during feeding. Cold blood flowing toward the body center within the periarterial veins would accept heat from warm blood in the central artery flowing toward the anterior end of the tongue. Although thermoregulatory systems have been identified within the mouths of a few mysticete species, the distribution of such vascular structures likely is more widespread among baleen whales than has previously been described.
Department of Biology, San Diego State University, San Diego, California; Department of Paleontology, San Diego Natural History Museum, San Diego, California.
Eric G
EG
Ekdale
Sarah S
SS
Kienle
D000818:Animals; D000831:Animals, Newborn; D001831:Body Temperature / Q000502:physiology; D001833:Body Temperature Regulation / Q000502:physiology*; D005260:Female; D012039:Regional Blood Flow / Q000502:physiology*; D014059:Tongue / Q000033:anatomy & histology* / Q000098:blood supply*; D014907:Whales / Q000033:anatomy & histology* / Q000502:physiology
Eschrichtius robustus; counter-current heat exchange; gray whale; rete mirabile; tongue