Transmission electron microscopy of presumed sensory receptors in the forebody papillae of Crepidostomum metoecus (Digenea: Allocreadiidae)

Abstract

Five types of presumed ciliate sensory receptors were detected in the forebody papillae of the adult fish trematode, Crepidostomum metoecus (Braun, 1900). The cilia are short and submerged in a tegumental pit. The apical bulb part of all types of receptors observed is supported by a dense collar and connected to the tegument basal plasma membrane by a circular septate junction. In sensory receptors types I and III no rootlet is present; the bulbs of sensory receptors types III and IV contain an electron-dense formation.