Structural and image analysis of a crystalline layer from dipteran eggshell.

A crystalline layer has been identified as a constituent of the eggshell in the dipteran Drosophila melanogaster. This 400A thick intermediate chorionic layer (ICL) is composed of eight 50A thick sublayers and lies between the vitelline membrane and the endochorion. Whole mount views of isolated ICL after negative staining reveal P2 planar periodicity which, when analyzed further by optical diffraction and filtering, showed 1st (100A), 2nd, 3rd and 4th order reflections.