Structural and Ultrastructural investigation on the digestive tubules of the freshwater mussel Caelatura parreyssi (Family: Unionidae) (Philippi, 1848) from the River Nile (Egypt).

The current investigation is concerning with the studying of the histology and ultrastructure of the digestive gland of the freshwater bivalve Caelatura parreyssi using light and transmission electron microscopes. This study was carried out on ten healthy clams, which were collected from the River Nile in Egypt. The specimens were dissected and small pieces of the digestive gland were selected out and processed for histological and ultrastructural examinations. The histological results revealed that the digestive gland of C. parreyssi is composed of numerous tubules, which are separated by connective tissues. Three types of cells were identified lined the digestive tubules; the digestive, excretory and crypt cells. Concerning the ultrastructural examination, digestive vesicles of different stages were seen that represent the characteristic features of the digestive cells. Excretory cells were distinguished by their excretory granules, whereas crypt cells showed spherules of calcium, which areconsidered also as characteristic ultrastructural feature.
In conclusion, the present study revealed that the digestive gland of the freshwater bivalve Cealatura parreyssi has many functions covering the digestion, secretion and excretion processes. Moreover, it has a detoxification role.