Cockroach molting. II. The nature of regeneration-induced delay of molting hormone secretion.

1. The amount of regenerating limb tissue does not control the length of molting delay in cockroaches; rather, a programmed delay associated with each autotomy level and segment allows an appropriate delay for accomplishing the necessary regeneration. 2. Delay of molting is accomplished by inhibiting ecdysiotropin release. 3. Each regenerating limb produces a delay independent of other regenerating limbs. 4. Single and simultaneous double autotomies can be used to obtain substantially increased synchrony of the molting cycle of a wide variety of cockroach species. 5. The signal to delay molting is transmitted to the brain along the ventral nerve cord and requires the stereotyped sensory input associated with autotomy to initiate it. 6. There are two phases of ecdysone titer increase during the molting cycle of cockroaches. An early transitory or gradual increase is associated with the regeneration critical period, while a later major peak is associated with apolysis. The major ecdysone peak was shown to be delayed during leg regeneration.