Gross and microscopic anatomy of the tongue and gastrointestinal tract of the bowhead whale (Balaena mysticetus)

Abstract

Typescript (photocopy).The tongue, esophagus, gastrointestinal tract and anal canal were examined grossly and microscopically in the bowhead whale, Balaena mysticetus. The tongue was a prominent, spindle-shaped, muscular organ lined by a partially keratinized stratified squamous epithelium. The esophagus was a muscular tube whose mucosa consisted of a stratified squamous epithelium as well as mucoserous glands and lymphatic nodules. The stomach was comprised of four compartments: a nonglandular forestomach lined by a keratinized stratified squamous epithelium; a fundic chamber containing the proper gastric glands; a narrow tubular connecting channel containing mucosal mucous glands; and a larger tubular fourth compartment, the pyloric chamber, also lined by mucous glands. The pyloric sphincter separated this final gastric chamber from the small intestine which began as a dilated sac, the duodenal ampulla, lined by mucous glands and devoid of villi. The duodenum continued after the ampulla in a more typical, tubular fashion and was lined by villi and crypts. The hepatopancreatic duct joined the duodenum shortly following the termination of the ampulla, traveling intramurally before joining the duodenal lumen. The small intestine ended with the sudden dilatation of the colon in the absence of a cecum. The colon was lined by typical straight, unbranched tubular glands. The anal canal was lined by a partially keratinized stratified squamous epithelium and contained numerous crypt-associated clusters of lymphatic nodules within its wall