Fig. 2. Effect of H-MW-HA on the 5-FU-induced intestinal mucosa damage.

Histological changes in the intestinal villi were determined using H&E staining. A Representative microphotograph showing the histologic section of a transversely cut intestinal segment of the control animal. B Representative microphotograph showing the histologic section of a longitudinally cut intestinal segment of a control animal. The tunica propria forms the core of the villi and consists of connective tissue, elastic and reticular fibers and lymphoid cells, below which extends the muscular mucosa consisting of smooth muscle cells. Beneath the mucosa lies the tunica submucosa, a layer of loose to dense connective tissue containing blood and lymphatic vessels. Tunica muscularis is the outer covering layer of the intestine and consists of two thick layers of smooth muscle. Structural landmarks: Villi (V), Crypts (C), lamina propria (LP), Tunica muscularis (TM). C Representative microphotograph showing histological appearances of the intestinal mucosa of control (A), H-MW-HA-treated (B), 5-FU-treated (C), and H-MW-HA + 5-FU-treated (D) mice. Compared with control mice, the innermost layer was largely destroyed in 5-FU treated mice (C), and the epithelial thickness was reduced (epithelial atrophy), with the villi length shortening and thinning of lamina propria (black arrows) with inflammatory cell infiltration. The same histological aspects were confirmed in multiple Control (A), H-MW-HA-treated (B), 5-FU-treated (C), and H-MW-HA + 5-FU-treated (D) group. D Intestinal thickness measurements; 1, villus length (yellow line); 2, tunica mucosa thickness (black line); 3, crypt depth (blue line).