| Popis: |
Detailed functional morphology of the digestive system of the thiarid snail Mieniplotia scabra is given in this study. The basic anatomical structure is consisting mainly of the mouth opening, the buccal mass, the salivary gland, the esophagus, the stomach, the style sac, the digestive gland, the intestine and the rectum. It confirms to that of any other style – bearing caenogastropods. The muscular structure of the buccal mass of the present snail has been macro and micro anatomically studied. Their structure has been correlated with their function and with the mechanism of feeding. It has been compared with the corresponding constituents of other caenogastropods mainly in family Thiaridae. The esophagus is an almost long tube and divided into three parts; pro - mid-, and post esophagus. The absence of the esophageal pouches and the crop of the alimentary canal of the present species reveal that the present snail is not adapted for cilliary feeding. The main structure of the stomach and the style sac resembles to those described in other thiarid snails. The detailed microanatomy and function of the epithelial lining of the digestive tubules of the digestive gland vary from one group to another thiarid snail according to the mode of feeding and digestion. Thus, in the present style - bearing microphagous herbivorous species the cells of the digestive tubule can be found in any one of the following three phases of activity; absorption, digestion and excretion. Therefore, they may be mainly adapted for intracellular digestion, absorption and excretion. The pro - intestine with its typhlosole, the post - intestine and the rectum have a simple histological structure; each being basically formed of a simple ciliated columnar epithelium with mucus-secreting cells and an outer muscular coat. The anal papilla characterized by the relatively thick muscular coat and long cilia of the epithelial lining. |
