title: Effect of Age on Body Wall Cuticle Morphology of Heterodera schachtii Schmidt females.
abstract: Fine structure of the body wall cuticle of Heterodera schachtii is compared with respect to age and body region of the female. The cuticle is more complex than previously reported. In newly molted females only layers A, B, and C are present, but 4 weeks after the final molt a thin D layer is present between the midbody and base of the cone. This D layer is absent in the cone of H. schachtii, regardless of age. As females age, an additional layer E is produced and includes zones E and E. Zone El apparently is unique to H. schachtii, whereas E is likely to be homologous with a similar layer in Atalodera. In the cone of old females (ca. 8 weeks after the final molt) of H. schachtii, the two zones become irregular in shape and comprise bullae. The presence of a thin D layer in Heterodera strengthens the previous hypothesis of a single ancestor of cyst nematodes.
authors.forename: D A
authors.initials: DA
authors.lastname: Cordero C
authors.forename: J G
authors.initials: JG
authors.lastname: Baldwin