Insect cuticular sclerotization: A review

Different regions of an insect cuticle have different mechanical properties, partly due to different degrees of stabilization and hardening occurring during the process of sclerotization, whereby phenolic material is incorporated into the cuticular proteins. Our understanding of the chemistry of cuticular sclerotization has increased considerably since Mark Pryor in 1940 suggested that enzymatically generated ortho-quinones react with free amino groups, thereby crosslinking the cuticular proteins. The results obtained since then have confirmed the essential features of Pryor's suggestion, and the many observations and experiments, which have been obtained, have led to a detailed and rather complex picture of the sclerotization process, as described in this review. However, many important questions still remain unanswered, especially regarding the precise regional and temporal regulation of the various steps in the process.