Induction of evisceration in the holothurianEupentacta Quinquesemita and evidence for the existence of an endogenous evisceration factor

The stimuli provoking evisceration of Eupentacta quinquesemita (Selenka) and
autotomy of isolated pharyngeal retractor muscle (PRM) tendons were investigated.
Tendon autotomy is a two-part response involving PRM contraction and breakdown
of tendon connective tissue . An evisceration factor (EF) was detected in coelomic
fluid expelled during evisceration. EF was isolated in tissue extracts and the haemal
system and peritoneum were sources of EF activity. Autotomy and evisceration were
induced by electrical stimulation, K+ and EF, and the effect of these agents was
inhibited by anaesthetics. The acetylcholine antagonist tubocurarine chloride
elicited evisceration, suggesting that evisceration may involve inhibition of cholinergic
transmission. Evisceration and autotomy appear to be neurally controlled and
the presence of an endogenous EF suggests neurosecretory or hormonal activity .
Cells involved in evisceration may be located at a distance from the autotomy tissues
and effect connective tissue breakdown through the medium of the coelomic fluid. Hypothetical sequences of events and possible roles for EF are presented.