We have carried out histological studies of the gastrointestinal tract of Laotian rock rat Laonastes aenigmamus. Most of the inner surface of the stomach is a cardiac region having reduced glands. Generally the cardiac glands are located near the esophagus. The esophagus and the ventricular groove are lined by keratinized stratified squamous epithelium. The region containing fundic (proper gastric) glands occupies a small area of the stomach. The maximum thickness of the gastrointestinal wall has been determined for the hindstomach and duodenum. The minimum wall thickness has been determined for ileum, colon, and cecum. In the large intestine, the glands are weakly developed and this can mean that there is not an active digestion in this gut site. Our results confirm the fact that foregut fermentation is crucial in digestion for this rodent. The topography of the regions, occupied by different types of mucosa in the stomach, has a convergent similarity to ones that are found in ruminant-like marsupials and points to similar adaptations to the consumption of plant foods. Owing to the small body mass of the rodents, the distribution of foregut fermentation is exceptionally rare in evolutionary history.

Digestive system, anatomy, histometry, evolution, Laonastes aenigmamus