ULTRASTRUCTURE AND FUNCTION OF THE PHARYNX OF GNATHOSTOMULA-PARADOXA (GNATHOSTOMULIDA)

The pharynx of Gnathostomula paradoxa consists of the partly syncytial pharyngeal musculature, a pharyngeal epithelium, myoepitheliocytes, r eceptors, nerves, and three solid parts, called the jugum, the basal p late, and the jaw. Extended non-contractile regions of both pharyngeal and body wall musculature form the so-called parenchymatous tissue be tween the digestive tract and the body wall, The pharyngeal epithelium mediates the force from the pharyngeal musculature to the solid parts , The basal plate and jaw contain longitudinal cuticular rods which ar e elastic antagonists of the musculature. There is no buccal ganglion in G. paradoxa. The study supports the monophyly of the Gnathostomulid a and Gnathifera.