PEROXISOMES AND PEROXISOMAL ENZYMES ALONG THE CRYPT-VILLUS AXIS OF THE RAT INTESTINE

The development of peroxisomes and expression of their enzymes were in vestigated in differentiating intestinal epithelial cells during their migration along the crypt-villus axis. Sequential cell populations ha rvested by a low-temperature method were identified by microscopy, det ermination of alkaline phosphatase and sucrase activities and incorpor ation of [H-3]-thymidine into DNA. Ultrastructural cytochemistry after staining for catalase activity, revealed the presence of peroxisomes in undifferentiated stem cells located in the crypt region. Morphometr y indicated that the number of these organelles increased as intestina l epithelial cells differentiate. Catalase activity was higher in the crypt cells than in the mature enterocytes harvested from villus tips. On the other hand, an increasing gradient of activity was observed fr om crypts to villus tips for peroxisomal oxidases, i.e. fatty acyl coA oxidase, D-amino acid oxidase and polyamine oxidase. These findings i ndicate that biogenesis of peroxisomes occurs during migration of inte stinal epithelial cells along the crypt-villus axis and that peroxisom al oxidases contribute substantially to the biochemical maturation of enterocytes.