Histology of small intestine

The wall of the small intestine of frog consists of the same four layers as seen in the wall of stomach. Serosa is very well developed. The circular muscles layer of the muscular coat is quite thin. The submucosa consists of connective tissue having a large number of highly branched arteries, veins and lymph vessels. The mucosa is projected into a large number of slender projected folds towards the lumen of intestine. These folds are lined by columnar epithelial cells many of which act as intestinal secretory cells secreting intestinal juice and mucus while the others act as absorptive cells or mucus secreting goblet cells. These folds very greatly increase the absorptive surface area of the intestinal mucosa. The muscularis mucosa is very poorly developed in the intestine.