NEMATODES

taxonomy, morphology and phylogeny

ULTRASTRUCTURE OF THE BUCCAL CAVITY AND THE CUTICLE OF 3 CEPHALOBIDAE (NEMATODA, RHABDITIDA)

Publication Type:Journal Article
Year of Publication:1994
Authors:M. C. VandeVelde, DeLey, P., Mounport, D., Baujard, P., Coomans, A.
Journal:NematologicaNematologica
Volume:40
Pagination:541-563
Date Published:Oct
ISBN Number:0028-2596
Accession Number:WOS:A1994PP39100008
Abstract:

The ultrastructure of the buccal cavity was elucidated in three species of cephalobids, two belonging to the genus Acrobeloides and one to the genus Chiloplacus. The cuticular differentiations, as well as the identity of the surrounding structures or tissues are used to identify the consecutive buccal regions. Six distinct buccal regions are discernible rather than the five parts generally assumed to be characteristic for many nematodes. The first buccal region is surrounded by the lip cuticle in which three sclerotized plates (two in a dorsosublateral position and one in a medioventral position) are embedded. The second buccal region is surrounded by two consecutive rings of arcade epidermis. The posterior arcade epidermis contains an electron-dense ring that surrounds the buccal cuticle and partly penetrates the junction of the cuticle and the anterior set of pharyngeal muscles. The basal lamina layer separating pharyngeal musculature from the other tissue components in the labial region ends as it contacts the electron-dense ring. The fourth to the sixth buccal regions are surrounded by four consecutive sets of pharyngeal muscles. The two anterior sets (m1 and m2) are composed of one muscle per pharyngeal sector, while the two posterior sets (m3 and m4) contain two cells per sector, interradially separated by cell membranes. Marginal cells, containing electron-dense radial fibres, are situated in a perradial position, thus separating the muscle cells. The anteriormost set of marginal cells spans the length of the four anterior muscle sets. The dorsal gland opens into the buccal lumen by means of a narrow canal situated at the anterior margin of the dorsal m4 muscle set. A neuronal cell process is situated just anterior to the canal. It is proposed that the observed buccal organisation does not fit the current concepts related to the homology of buccal parts in nematodes.

Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith