Structure of the Cuticle of Metadasynemoides cristatus (Chromadorida: Ceramonematidae)


  • Warwick L. Nicholas
  • Aimorn C. Stewart


Structure of the cuticle of Metadasynemoides cristatus (Chromadorida: Ceramonematidae) is examined by light, scanning, and transmission electron microscopy. The nematode has more than 600 annuli, and each annulus has eight cuticular plates. Eight longitudinal ridges, beginning on the cephalic capsule, extend the whole length of the body. Where a ridge traverses an annulus, it forms a complicated articulating structure of overlapping vanes. Within the electron-dense cortical layer, from which the cuticular plates are formed, there are spaces crossed by fine fibrillae, forming what have been termed "vacuoles" by light microscopists. There is an epicuticle and a continuous lucent basal layer. There appears to be no median layer. The cuticle lining of the esophagus and that forming the circum-oral ridge is of much simpler construction. Key words: annulation, cuticle, light microscopy, marine nematode, Metadasynemoides cristatus, scanning electron microscopy, transmission electron microscopy, ultrastructure, vacuole.