Neuroendocrine control of insect ecdysis by eclosion hormone
1996
Horodyski, F.M.
The peptides eclosion hormone (EH) and ecdysis-triggering hormone (ETH) trigger ecdysis behaviors and other physiological changes which occur at the end of the molt. EH is synthesized in a discrete set of cerebral neurosecretory cells, and is released into the central nervous system and into the hemolymph in response to the declining ecdysteroid titers. The onset of behavioral sensitivity to EH action is similarly controlled by ecdysteroids. EH is released from the ventral nerve cord for larval and pupal ecdyses, and from the corpora cardiaca for adult ecdysis. This transition is mediated by the restructuring of the EH cells during adult development, so that they elaborate an axon which extends to the CC for storage and release of EH just prior to adult ecdysis. ETH is released from the Inka cells, a component of the segmentally paired epitracheal glands, and acts directly on the central nervous system (CNS) to trigger preecdysis and ecdysis behavior. Although EH is best understood in lepidopteran insects, accumulating evidence suggests that EH is present in all insects and may provide a general hormonal mechanism to regulate ecdysis.
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