Figure 7
Pyloric caeca of S. fuscus. (A) Insertion of caeca (a) in bolsa serosa (b) common to pyloric stomach (c), conjunctive of serosa originating the lamina propria of caeca (arrow); (B) pyloric caeca with mucosa containing numerous folds; (C) caeca with simple ...
3.2.3. Intestine
The intestine is moderately long and thin which is typical of herbivorous fish. It forms four folds around the stomach, with their circumvolutions joined by adipose tissue. The estimated mean intestinal coefficient is 2.18 ± 0.15. Though S. fuscus does not exhibit a very long intestine, the long folds observed from the caeca to the intestine could be responsible for efficient nutritional absorption. The anterior intestine has folds similar to those identified in the pyloric caeca, but they branch off (Figure 8(A)). The epithelium is cylindrical with a greater number of goblet cells (Figure 8(B)); however, glands are absent in the mucosa and submucosa. After the lamina, propria is the muscle layer, consisting of an inner circular tunica and an outer longitudinal tunica of smooth muscle tissue. The last layer is the serous membrane. In the distal part of the intestine, the folds are smaller, but the muscle layer is thicker (Figures 8(C) and 8(D)).