Chorionic structure of Dineutes hortii Rbts. (Coleoptera: Gyrinidae)

Abstract

Unlike other gyrinid species, the chorionic surface of Dineutes homi is covered with blunt conical projections. The micropylar region consists of a stalk-like structure in the center of a depression. Internally the chorion consists of an exo-and endo-chorion. The outer chorion has large spaces and is composed of a laminated and porous material, whereas the inner chorion is made-up of a thick granulated layer and a thin electron-dense layer. The vitelline membrane has an electron-dense upper surface and spherical, vesicular-like structures that are dispersed throughout the membrane. © 1987 Taylor & Francis Group, LLC.