CHEMICAL CONTROL OF THE EVISCERATION PROCESS IN THYONE BRIAREUS

¹ Department of Zoology and Scarborough College, University of Toronto, West Hill, Ontario, Canada; Department of Biological Sciences, Florida State University, Tallahasse, Florida 32306; and the Marine Biological Laboratory, Woods Hole Massachusetts 02543

1. The pharyngeal retractor muscles of Thyone briareus autotomize during evisceration at the junction of the PRM and LBWM. Autotomy involves a loss of tensile strength at the connection between the PRM and the LBWM.

2. An evisceration factor (EF) is present in the coelomic fluid expelled by eviscerating Thyone. This factor induces autotomy of isolated PRMs.

3. Most tissues have some EF activity, but haemal system is the richest source of the factor.

4. Purified EF causes evisceration on injection into intact animals.

5. The factor is a small molecule (~150 MW), of unknown character. It probably has other roles in muscle and connective tissue physiology.

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