Morphology of the digestive system of the lesser bamboo rat (Cannomys badius)

The lesser bamboo rat is a fossorial rodent within the monotypic genus Cannomys, family Spalacidae and is found in Indochina. The present work provides the first detailed description of the morphology of its digestive system, as examined by gross dissection and histological examination. The oesophagus was lined by a heavily keratinized epithelium and contained mostly striated muscles in the muscularis externa. The stomach was of the unilocular-hemiglandular type with a cornified squamous area at the fundus separated from the glandular area by the limiting ridge. The length ratio of the small intestine to the entire intestine was relatively low compared to that in other rodents. The caecum contained five to seven haustra and numerous lymphoid tissues, but no distinct appendix. Within the long colon, two non-papillated longitudinal folds forming a colonic groove, V-shaped mucosal folds like fishbones and abundant goblet cells were apparent. A five-lobed liver with a gallbladder and a diffuse pancreas were evident. These findings may indicate that the lesser bamboo rat is a caecal fermenter capable of feeding on highly abrasive plant material. Fermentation may take place via a mucus-trap colonic separation mechanism without coprophagy. The digestive system of the lesser bamboo rat is somewhat different from that of spalacid relatives.