Tarpley R J, Sis R F, Albert T F, Dalton L M, George J C
Department of Veterinary Anatomy, College of Veterinary Medicine, Texas A&M University, College Station 77843.
Am J Anat. 1987 Nov;180(3):295-322. doi: 10.1002/aja.1001800310.
Gastric and cranial duodenal structure of the bowhead whale (Balaena mysticetus) was examined grossly and microscopically. The stomach was arranged in a series of four compartments. The first chamber, or forestomach, was a large nonglandular sac lined by a keratinized stratified squamous epithelium. It was followed by the fundic chamber, a large, somewhat globular and entirely glandular compartment. At the entrance of the fundic chamber, a narrow cardiac gland region could be defined. The remaining mucosa of the chamber contained the proper gastric glands. A narrow, tubular connecting channel, the third distinct gastric division, was lined by mucous glands and joined the fundic chamber with the final stomach compartment, or pyloric chamber. This fourth chamber was also tubular and lined by mucous glands but was of a diameter considerably larger than the connecting channel. The stomach terminated at the pyloric sphincter which consisted of a well-developed band of circular smooth-muscle bundles effecting a division between the pyloric chamber and small intestine. The small intestine began with the duodenal ampulla, a dilated sac considerably smaller than the fundic chamber of the stomach. The mucosa of this sac contained mucous glands throughout. The ampulla led without a separating sphincter into the duodenum proper which continued the intestine in a much more narrow tubular fashion. The mucosal lining of the duodenum was composed of villi and intestinal crypts. Although their occurrence varied among whales, enteroendocrine cells were identified within the mucous glands of the cardiac region, connecting channel, pyloric chamber, and cranial duodenum. The hepatopancreatic duct entered the wall of the duodenum shortly after the termination of the duodenal ampulla and continued intramurally along the intestine before finally joining the duodenal lumen.
对弓头鲸（Balaena mysticetus）的胃和十二指肠头部结构进行了大体和显微镜检查。胃由一系列四个部分组成。第一个腔室，即前胃，是一个大的非腺性囊，内衬角质化的复层鳞状上皮。接着是胃底腔，这是一个大的、有点球形且完全为腺性的腔室。在胃底腔的入口处，可以界定一个狭窄的贲门腺区域。该腔室的其余黏膜含有固有胃腺。一个狭窄的管状连接通道，即第三个明显的胃部分，内衬黏液腺，将胃底腔与最后一个胃部分，即幽门腔相连。第四个腔室也是管状的，内衬黏液腺，但直径比连接通道大得多。胃在幽门括约肌处终止，幽门括约肌由发育良好的环形平滑肌束带组成，在幽门腔和小肠之间形成分隔。小肠始于十二指肠壶腹，这是一个比胃底腔小得多的扩张囊。这个囊的黏膜全程都含有黏液腺。壶腹无分隔括约肌地通向十二指肠本部，十二指肠本部以更狭窄的管状形式延续肠道。十二指肠的黏膜内衬由绒毛和肠隐窝组成。尽管在不同鲸鱼中其出现情况有所不同，但在贲门区域、连接通道、幽门腔和十二指肠头部的黏液腺内都发现了肠内分泌细胞。肝胰管在十二指肠壶腹终止后不久进入十二指肠壁，并在肠壁内沿着肠道继续前行，最终汇入十二指肠腔。
