Interacting Factors in the Control of the Crustacean Molt Cycle

In order to account for the known phenomena of the crustaceanmolt cycle, at least six factors must be postulated: a moltinghormone (20-OH-ecdysone), a molt-inhibiting hormone (MIH), ananecdysial limb autotomy factor, a proecdysial limb-autotomyfactor, a limb growth-inhibiting factor and an exuviation factor.Only the molting hormone and its derivatives have been chemicallywell defined. The various factors interact in complex ways tomaintain not only a coordinated proecdysial period in preparationfor exuviation but also a proecdysial period with the flexibilityto respond to such interim hazards as the loss of partiallyregenerated limbs.