ULTRASTRUCTURE OF THE BODY WALL OF ANCYROCEPHALUS MOGURNDAE (MONOGENEA:ANCYROCEPHALIDAE)

The body wall of the monogenean, Ancyrocephalus mogurndae, parasitic on the mandarin fish, Siniperca chuatsi, consists of a syncytium, a basal lamina with circular and longitudinal muscles and pericaryon. The infolded apical plasma membrane forms tegumental ridges on both the ventral and dorsal surfaces. The infolded basal plasma membrane forms numerous finger like projections through the syncytium. A thin coat of glycocalyx is present on the tegument surface. The syncytium contains four kinds of secretory bodies, i.e. the electron dense granules, the moderately electron dense granules, the electron lucent vesicles and the multivesicular bodies. Exocytosis of the electron dense granules, the multivesicular bodies and the syncytial cytoplasm apparently occurs in the syncytium of the general body surface. The absence of pino and phagocytotic vesicles from the tegument suggests that excretion or osmoregulation is the primary function of the tegument, but not nutrient uptake. The presumed non ciliated sensory papilla on the lateral head lobe consists of an ellipse shaped structure situated beneath the thin tegument with the smooth basal lamena. A large versicular body, numerous granules and vesicles and the electron dense cytoplasmic mass are observed in the ellipse shaped structure. Nerve process is rich in the vicinity. It is suggested that this kind of papilla may play a role in attachment.