Electron Microscopy of the Stomatostylet and Esophagus of Criconemoides curvatum

Abstract

The stomatostylet of Criconemoides curvature consists of three parts: tooth cone, shaft, and knobs. The tooth cone constitutes the outer conical covering and inner lining of the anterior half of the stylet lumen. The tooth cone is easily separated from the shaft by treating an isolated styler with 0.5% sodium hypochlorite. The posterior half of the shaft is cylindrical, tapering anteriorly to form the shaft extension, wedged between the inner and outer tooth cone. The shaft extension extends to the stylet lumen orifice, which is subterminal and ventral. Six ducts enter the shaft through the junction between the shaft and knobs. They extend anteriad toward the tip of the shaft extension. Cytoplasmic connections between the ducts and the cells surrounding the stylet occur near tile junction between the shaft and the basal knobs. Ribosome and membranous structures are observed in these ducts. The esophagus of the adult female consists of a fused procorpus and metacorpus with a large valve possessing thickened cuticular walls at the anterior and posterior ends. The dorsal esophageal gland reservoir is composed of many honeycomb-like compartments made up of two types of differing electron density. The subventral esophageal glands, however, consist of only one type of granules. Both dorsal and subventral esophageal glands open into the esophageal lumen through trachea-like branched multiple canals. Key Words: stylet, esophageal glands, ultrastructure.