Structure and Formation of the Chorion in Parnassius glacialis (Lepidoptera, Papilionidae)

Morphology and morphogenesis of the chorion of Parnassius glacialis were described. Architecture and thickness of the chorion vary remarkably in different regions. A single micropylar opening leads into 3 canals penetrating the chorion and the vitelline membrane. Aeropyles are seen at the junction of 3 ridges of the chorion. The chorion is composed of 3 layers : an inner, a middle and an outer layer. The middle layer is distinguished as two sublayers and made up of 8 or 9 lamellae. The lamellar structure is thought to be due to serial production of secretions by the follicle cells. The micropylar apparatus is formed by 3 types of the micropyle-forming cells.