CHANGES IN INTESTINAL TUNICA MUSCULARIS FOLLOWING DIETARY FIBER FEEDING IN RATS - A MORPHOMETRIC STUDY USING IMAGE-ANALYSIS

The morphological changes in the intestinal tunica muscularis induced by prolonged dietary fiber intake were determined in rat small intesti ne and colon with the aid of computerized image analysis. Thirty male Sprague-Dawley rats were fed either a fiber free, 15% cellulose or 15% pectin diet for 8 weeks. Intestine length was measured and stained cr oss sections of the jejunum, ileum, and colon were quantitated using i mage analysis. In the distal colon, muscle cell size was also determin ed. Despite lower weight gain in the pectin fed rats, both the small i ntestine and colon length were significantly increased. Cellulose feed ing had a lesser effect on intestine length. Pectin fed rats had signi ficantly increased relative tunica muscularis area (37.2 +/- 2.2 mm(2) ) in ileum cross sections when compared to control (24.3 +/- 1.8 mm(2) ) and cellulose fed rats (26.1 +/- 1.1 mm(2)). In the mid-colon, the t unica muscularis area was found to be pectin > cellulose > control (33 .5 +/- 2.2; 29.7 +/- 1.7; 25.8 +/- 1.5 respectively) with significant differences reached between pectin and control rats. In jejunal sample s, no differences were observed among the groups. Circular smooth musc le cell size in the distal colon was significantly increased following cellulose feeding but was less pronounced in the case of pectin. We c onclude that fiber supplementation leads to morphological changes in t he rat intestine including changes in length and tunica muscularis vol ume.