The chorion of the eggs of Ceratitis capitata, has been studied with scanning and transmission electron microscopy.This study reveals some srructural differences between the micropylar area and main body of the egg. The chorion consists of three layers: Exochorion, endochorion and innermost chorionic layer. At the micropylar area, the whole thickness of corion is five times thicker than is on the body of the egg. The cavities of endochorion are more abundant in the micropylar area. The endochorion of the main body has two interconnected trabecular layers. There is an intermediate zone, where the cavities of two trabecular layers are not connected to each other,similar to the endochorionic layer of the micropylar area.The morphology of the egg shell of C. capitata is discussed in relation to the egg resistence to varying concentrations of electrolytes and its permeability, compared with other Diptera

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