Cuticular sclerotization in insects

The insect cuticle is an extracellular structure covering the total outer surface of the animal and providing protection against harmful influences from the environment. The mechanical properties of cuticles may vary considerably, and pronounced regional differences are generally observed. The properties may also change during development, and it can be assumed that the physical and chemical properties of all cuticular regions tend to be close to the optimal for proper physiological function during all developmental stages. Cuticular regions can be stabilized by the process of sclerotization, whereby o-diphenols are oxidatively incorporated into the material. Our current knowledge of the sclerotization process is reviewed, and it is suggested that the main features of the chemistry of sclerotization probably have been established, and that the major questions now remaining concern the precise regional and temporal control of the process.