Aspects ultrastructuraux de la biodegradation de l''ancienne cuticule de Carcinus maenas durant la periode preecdysiale

Ultrastructural observations of various integumental regions of the crab Carcinus maenas show an important biodegradation of the old sclerites during premolt. At the ecdysis, this biodegradation extends from the basis of the membranous layer up the upper third of the principal layer. The first biodegradation features are a disorganization followed by a complete disappearance of the microfibrils. Numerous ecdysial droplets and double membrane bounded microstructures probably take part in biodegradation processes.