Adaptations of the caecum-colon structure of rodents

Abstract

1. 1. The gross anatomy of the caecum-colon structure of some rodents revealed that all Cricetidae examined possess a post-caecal spiral which is absent in the Muridae studied. 2. 2. The length of colon, i.e. from caecum to anus, is longer in the Cricetidae than in the Muridae. 3. 3. The size and appearance of the post-caecal spiral has been related to the ecology of the animals, e.g. the large post-caecal spiral and the long colon in the Norway lemming, Lemmus lemmus (L.), may reflect demands caused by the low ash content of the food preferred by this animal. 4. 4. Sodium, potassium and water absorption, and the relative efficiency of absorption, in the caecum-colon structure of the Norway lemming and the Norway rat, Rattus norvegicus (L.), have been studied. Relatively, the absorption of sodium and potassium is more efficient in the Norway lemming than in the Norway rat. 5. 5. Water is being efficiently absorbed in the caecum-colon structure of both the Norway lemming and the Norway rat, and, apparently, the amount of water absorbed can be accounted for by a “solute-linked” mechanism.