Correlative morphometry and morphology of normal equine intestinal mucosa and comparison after adaptation to extensive large colon resection.

Light microscopy, morphometry and scanning electron microscopy (SEM) were used to examine the mucosal morphology of seven intestinal specimens (three from the small intestine and four from the large intestine) from two horses not subjected to surgery and three horses one year after sham-operation for colon resection. Qualitative and quantitative evaluation revealed similar morphology for all horses except that the unoperated horses had significantly (P < 0.05) fewer goblet cells in the crypts of the large intestine. In the small intestine, SEM demonstrated that villus shape varied and ranged from coned to broad and flat. In the large intestine, SEM of the right ventral and dorsal colon revealed more prominent crypt openings than in the caecum. The small colon contained the most prominent crypt openings with the least variation among horses. In the small intestine, light microscopy and morphometry revealed a greater number of goblet cells and a decreased width to the enterocytes in an aboral direction from the cranial jejunum to the ileum. In the large intestine, the crypt area and crypt depth increased significantly and the intercrypt area decreased significantly in an aboral direction from the caecum to the small colon (P < 0.05). In comparison to the normal morphology, horses one year after extensive large colon resection had significantly greater intercrypt area in the caecum and remaining large colon.