Histology of different tissue of O. stentina: (A and B) visible hermaphroditic gonad with ripe female phase and developing male phase; vitellogenic ovocytes (Ov) and spermatogonia (Spg) are indicated; (C) digestive gland (DG) show a thick adsorbing epithelium sign of an active feeding; (D) Details of mantle epithelium (E) showing well developed mucous cells stained with acid alcian Blue Pas (black arrow) and eosinophilic granular cells (white arrow) part of the oyster first line of defense. CT: connective tissue.