Sécrétions cuticulaires et ecdystéroïdes chez les embryons decapités du phasmeCarausius morosusBr. / Ecdysteroids and cuticle secretions in decapitated embryos of the phasmidCarausius morosusBr.

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Abstract
Embryos of the phasmid Carausius morosus Br., deprived of their head at an early stage (V3, 27th day) of development live up to the 147th day when grown on their own vitello-serosal system. In these embryos, the 2nd embryonic cuticle characteristic of the dorsal closure stage, and the 3rd embryonic cuticle (1st larval cuticle) with its setae and procuticle, both have a typical structure. Thus the cephalic endocrine system of the embryo is clearly not indispensable either for 2nd and 3rd cuticle deposition, or for production of a typical ecdysteroid peak at the dorsal closure, or even for the rise of ecdysteroid level during the 3rd cuticle secretion. But in decapitated embryos this rise is not followed by a decrease as it is in controls. In both operated eggs and controls, the same free and conjugated 3 hormones were separated by HPLC and quantified by RIA: 20,26-dihydroxyecdysone, 20-hydroxyecdysone (main hormone in the phasmid) and ecdysone. Very similar quantitative results were obtained for controls and operated eggs at the dorsal closure stage. However, noteworthy differences were found between the two kinds of eggs concerning the respective levels of 20-hydroxyecdysone and of its conjugates during the 3rd cuticle secretion.

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