[Histological and morphometric study of the development of the optic part of the compound eye of the Enallagma boreale Selys (Odonata: Coenagrionidae)].

The morphology of the optical part of the Enallagma boreale Selys compound eye remains unchanged during its post-embryonic development. The cornea, composed of the epi-, exo- and endocorne, is in perfect continuity with the larval cephalic cuticle. Consequently these two structures possess the same three layers and have a similar process formation. But, the measurements from cephalic endocuticle and endocornea of the adult differ significantly from each other. The latter has a lamellar aspect. The nuclei cornea reaches its morphometric characteristics as early as the pre-emergence stage. The nuclei of the two primary pigment cells which have maintained their epidermic nature, are located at each side of the apex of the crystalline cone. The nuclei of the secondary pigment cells are uniformly distributed in the optical and photosensitive parts. The larval and adult crystalline cones differ morphometrically. The larval one is longer and narrower and reaches its adult characteristics just before emergence. Statistical tests do not show any significant difference between the dorsal and the ventral parts of the larval and adult compound eye.