Aspects of the anatomy and histology of the alimentary canal of the greater cane rat, Thryonomys swinderianus, with reference to its feeding physiology

Abstract

Aspects of the anatomy and histology of the alimentary canal of Thryonomys swinderianus were studied to gain a better understanding of this animal’s ability to digest large quantities of fibre. Morphometric measurements of the gut regions were taken with the aid of light, transmission and scanning electron microscopy. The stomach is fully glandular and unilocular with a low pH and is possibly the initial site of protein digestion. The duodenum, with its closely packed columnar cells with many mitochondria, may be the main site of enzymatic digestion. Owing to coprophagy, food and fermentation products are recycled for further digestion in the small intestine. The caecum is by far the largest region in mass and the apex ceci may be the main site of fermentation. A ridge-lined furrow is present inside the proximal colon. Thick muscle layers are present in the vicinity of the ridge-lined furrow. It is suggested that the furrow is part of the colonic separation mechanism that transports bacteria back to the caecum. The longitudinal folds and long villi in the proximal colon enlarge the surface area, where the columnar cells of the villi have many mitochondria, probably to absorb fermentation products and to transport water and electrolytes across the mucosa. In the distal colon many mucous cells open in tubular glands of Lieberkühn. Reabsorption of water probably occurs through the dense microvillous border.

Keywords: Thryonomys, alimentary canal, anatomy, histology, cane rat