General histology of small intestine (duodenum and jejunum) and the large intestine (colon and cloaca) of C. c. yacare (Daudin, 1802) Crocodilia-Reptilia. A comparative description is made of the histology of the small and large intestine of C. c. yacare. In all segments mucosa, submucosa, muscularis and serosa tunics were observed. The duodenum as very long villi, wich are well-developed and attached together to form irregular transverse ridges, covered with simple columnar epithelium with marginal and goblet cells. In the jejunum, the villi are shorter and less frequent. The colon as few folds, covered with the same epithelium; the lamina própria contains straight tubular glands with absortive cells, goblet and Paneth cells. The cloaca is very complex, with three well-defined regions: coprodeum, urodeum and proctodeum. In the coprodeum, the wall is folded, less muscular and the thin mucosa is covered by an epithelium with a few basal cells and mucosal cells. The urodeum as an additional external muscular tunic, with striated muscle fibers and a stritifield cylindrical epithelium with goblet cells. The proctodeum includes the free part of the penis in the male and, laterally, the ducts of a pair of holocrine cloacal glands. Near the opening of the ducts, the epithelium changes to a squamous keratinized type.