Comparative Fine Structure of the Stomatal Region of Males of Meloidogyne incognita and Heterodera glycines

Abstract

The fine structure of the stylet, "guiding apparatus," anti protractor muscles of males of Meloidogyne incognita attd Heterodera glycines is ehtcittated and compared. In both nematodes, the stylet cone is of greater electron density than the shaft. The cone is heterogeneous; shaft material extends into it for most of its length, whereas the shaft proper and knob regions are relatively homogeneous. The stylet lunen is round throughout its length in H. glycines, but in M. incognita changts from round, posteriorly, to irregular, triradiate, and oblong near the styler tip. The various layers of the lining of the stylet shaft are continuous with those of the cuticular lining of the esophageal lumen. Similarly, cuticular layers of the stomatal lining and vestibule extension are continuous with the body wall cuticle. The stylet "guiding apparatus" is formed by linings of the stomatal opening, vestibule, and vestibule extension, together with transversely folded membranes, which extend further posteriorly and attach near the junction of shaft and cone. Noncontractile regions of the three stylet protractor muscles originate in the esophagus. Contractile portions extend anteriorly from the stylet knobs and branch into a total of 10 elements that attach near the basal ring of the cephalic framework and the vestibule extension. A second, noncontractile region is present at the anteriormost part of the protractor muscles in H. glycines. Key Words: Cyst nematode, root-knot nematode, stylet, stylet "guiding apparatus," stylet protractor muscles.