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The buccal capsule of nematodes functions in the initial uptake of food into the alimentary tract. As such it shows many modifications in form dependent on the nature of food and feeding mechanism. Hence, buccal structures have been used extensively in taxonomic and phylogenetic considerations. The buccal capsule of rhabditoid nematodes has received considerable attention and a complex terminology, initially attributable to Steiner (1933), has developed to describe its form in various subgroups of the order Rhabditida. Most commonly the buccal capsule has been considered to include regions named the cheilostom, prostom, mesostom, metastom, and telostom. Attempts have also been made to extend this terminology (by implication, through homology) to other major nematode groups (e.g. De Coninck 1965; Coomans 1963; Ritter 1965), although pitfalls have been recognised (Coomans et al. 1978).
Recent anatomical studies using electron microscopy have noted marked differences between cuticle of the body wall and that of the nematode's esophagus (Dick and Wright 1973; Wright 1976). Although the buccal capsule of some groups may consist of only slight modification of anterior musculature of the esophagus which makes contact with the body wall directly at the oral opening, in others the body wall cuticle and underlying cells may infold into the buccal capsule to make contact with the esophagus some distance internally. With the extensive development of serial-section electron microscopy of Caenorhabditis elegans, and experimental studies of its development, it has been possible to analyse in more detail the structure of the buccal capsule and its formation during moulting. A previous study of the cellular composition of this nematode's esophagus (Albertson and Thomson 1976) formed a basis for part of this study.
Adapted by Yusuf KARABEY for WORMATLAS, 2003