The ultrastructure of the intestine of the redia of Parorchis acanthus Nicoll (Digenea: Philophthalmidae) from the digestive gland of Nucella lapillus L

Abstract

SUMMARYThe intestine of the redia of Parorchis acanthus is lined by a gastrodermis and surrounded by inner longitudinal and outer circular muscles. The gastrodermis consists of alternating rings of dense and lucent cells of similar dimensions, with similar nuclei and with microvilli on the lumenal surface. The dense cells contain ribosomes, dense secretion bodies, vesicles and a few lipid bodies. Ribosomes, dense bodies and lipids are absent from the lucent cells but vesicles are present which, as in the dense cells, pass along the microvilli to be discharged into the lumen. Both types of cells are secretory, absorptive and transportive. The lucent cells, in addition, store glycogen in areas of the cytoplasm devoid of organelles. Tips of processes from the parenchyma cells are engulfed in pockets in the basal plasma membrane, of both, facilitating transport of nutrients from the gastrodermis directly into the parenchyma