Morphological,histological and histochemical observation of digestive system in Mactra antiquata

The structure and function of the digestive system in Mactra antiquata were studied by anatomical,histological and histochemical methods.The digestive system consists of the digestive tract,which is composed of the labial palps,mouth,esophagus,stomach,style sac,intestine,rectum and anus,and digestive diverticula.Except the labial palps and style sac,the tract consists of mucous membrane,submucosa lamina,lamina muscularis and adventitia.There is no muscular layer in a part of the stomach and the intestine.The adventitia is composed of fibrosa,except serosa covering the wall of mouth,rectum and anus.The digestive diverticulae are compound tubuloacinar glands which connected to the stomach by a system of ducts.The glandular epithelium is comprised of four types of cells: embryo cell(E-cell),fibrillar cell(F-cell),absorptive cell(R-cell) and secretory cell(B-cell).The lumen of mouth,stomach and intestine and glandular cavity are filled with phagocytes.Intense alkaline phosphatase activity was detected in the epithelium of the intestine.The epithelia of stomach and intestine and ducts show strong activity of acid phosphatase.There are irons in the submucosa lamina of stomach and intestine and digestive diverticula.