Juxtaligamental system of the disc and oral frame of the ophiuroid Amphipholis kochii (Echinodermata: Ophiuroidea) and its role in autotomy

The ophiuroid Amphipholis kochii is able to detach its central disc from the underlying
oral frame in response to external stimuli. In this article we supply new observations
on the microanatomy and ultrastructure of the autotomy plane, and of the juxtaligamental
system which is believed to bring about connective tissue changes that underpin the detachment
process. We correct previous confusion over the innervation of juxtaligamental nodes
involved in disc autotomy, provide evidence that juxtaligamental cells are a population of
specialized nerve cells, and present observations on changes in the ultrastructure of juxtaligamental
cells during autotomy, which support the view that they are responsible for connective
tissue disruption.