Regional differences along the small intestine of the pigeon (Columba livia): histobiochemical evidences.

Mucosal surface area, protein, DNA and RNA content, [3H]-thymidine incorporation, total activity of glucosidases, peptidases, phosphatases and transaminases were measured in the duodenum and in the middle and lower parts of the small intestine of the domestic pigeon Columba livia. Mucosal surface area, protein, nucleic acid content and [3H]-thymidine incorporation were significantly higher in the duodenum and in the middle part of the small intestine than in the lower part. Whereas the activities of alkaline phosphatase, sucrase, cellobiase and lactase were significantly higher in the middle part of the small intestine, those of maltase, glucoamylase and leucine aminopeptidase were significantly higher in the lower part. It is concluded that in Columba livia small intestine, regional differences are more pronounced between the middle and the lower parts of the small intestine than between this middle part and the duodenum.