Fig. 2.

Alcian Blue staining on stomach epithelium of adult Ciona. Control animal, not DSS-treated (A,B), shows a thin and dense mucus layer on the surface of stomach epithelium (arrows). Glycoprotein-rich vesicles are strongly detected within the stomach grooves (A, delimited by rectangles) and spread along the epithelium, on the side closer to the gut lumen (B, triangles). Both 1% (C,D) and 0.5% (E,F) DSS-treated animals exhibit the epithelium characterized by the numerous furrows (arrowheads). In 1% DSS samples, a more intense blue staining is observed along the epithelium (C, arrow) and in cells that are more deeply located in the epithelial layer (D, triangles). Glycoprotein-rich granules are not detected in the grooves of stomach villi. In 0.5% DSS-treated samples, the mucus layer appears detached or loosely associated (E,F, arrows) and glycoprotein-rich granules are detected more deeply in the epithelium (F, triangles). The presence of CMPs during 0.5% DSS treatment reduced the formation of furrows on the epithelial surface (G, arrowhead), although a loosely associated mucus layer is still observed (H, arrow). Glycoprotein-rich granules are localized in the stomach grooves (G, rectangles) and less in the basal side of the epithelium (H, triangles). Stomach sections of animals treated with CMPs (I,J) reveal an epithelial morphology similar to that observed in control animals. n=6, animals observed for each condition. Asterisk indicates stomach lumen; rectangles, grooves of the stomach epithelium; black arrow, mucus layer; arrowhead, furrows; triangles, granules along the epithelium. Scale bars: (A,C,E,G,I) 50 µm; (B,D,F,H,J) 25 µm. Right images are magnification of the left images.