The anatomy and histology of the midgut and hindgut of Charybdis (Goniohellenus) truncata (Fabricius, 1798) (Decapoda: Brachyura).

The midgut of C. (G.) truncata accounts for half of the postgastric intestinal tract. The paired anterior midgut caeca arise just behind the pyloric stomach, on either side of the midgut. The unpaired posterior midgut caecum arises dorsally at the rear end of the midgut, where this joins the hindgut. The midgut and its caeca help in the digestive absorption of food. The hindgut is of ectodermal origin and is lined with chitin of a collagenous nature. The connective tissue of the anterior part of the hindgut is packed with tegumental glands whose secretion contains both sulphated and weakly acidic mucosubstances, which facilitate the passage of faecal matter and help to bind food particles. The digestive gland - the hepatopancreas - opens into the anterior part of the midgut, below the anterior midgut caeca. Histologically, its tubules contain three different types of cells - "F", "R" and "B" cells.