Ultrastructural localization of thiamine pyrophosphatase activity in the intestinal epithelial cells of adult rats.

Ultrastructural localization of thiamine pyrophosphatase (TPPase) activity was studied in the small and large intestinal epithelial cells of adult rats. In the duodenal and jejunal absorptive cells, TPPase activity was localized on the microvilli, on the lateral cell membrane, and on the lysosome-like bodies. In the ileal epithelial cells, TPPase activity was detected on the lysosome-like bodies, and weak phosphatase activity was observed on the microvilli and on the cisternae of the rough-surfaced endoplasmic reticulum (rER). In the principal cells of the caecum, the ascending colon, and the descending colon, the lysosome-like bodies and the cisternae of the rER showed TPPase activity. Almost all Golgi lamellae, vesicles and GERL elements (NOVIKOFF 1964) in the duodenal absorptive cells were strongly TPPase positive. The 1st to 3rd of the inner Golgi lamellae and the vesicles of the jejunal, ileal, and large intestinal epithelial cells usually showed positive TPPase activity, while the GERL elements were totally negative.