Ultrastructure and reconstruction of the pharynx of Leptonemella juliae (Nematoda, Adenophorea)

Abstract

The pharynx of Leptonemella juliae is the first pharynx of Adenophorea that has been reconstructed three-dimensionally using TEM serial sections. It is composed of a slightly swollen corpus, a median narrow isthmus, and a pronounced terminal bulb. At its anterior end, the lumen of the pharynx opens into a small buccal cavity without any specific cuticular differentiation, while at the posterior end it is separated from the intestine by a pharyngeo-intestinal valve. The entire pharynx epithelium is delimited from the pharynx lumen by cuticle and from the remaining body by extracellular matrix. The main cellular components of the pharynx of L. juliae are: the radial epithelio-muscle cells and the marginal cells, two subventral and one dorsal gland cells, the nervous system, which consists of six longitudinal nerves stretching from anterior to posterior, one horseshoe-shaped commissure, three nerve rings, and three pharyngeal sensory structures (PSS). The ultrastructure and location of gland cells, the sensory structure, and the nervous system appear to be character complexes of value for comparative anatomy. A detailed description of the PSS is presented.