ABSTRACT
The various ligaments that link together the outer plates of the ophiuroid arm consist of mutable collagenous tissue (MCT). Accordingly, an ultrastructural comparison of these two ligaments is being conducted in order to provide insight into the morphological correlates and macromolecular mechanism of variable tensility in MCTs. Both the distal oral arm plate ligament (DOL) and proximal oral arm plate ligament (POL) contain juxtaligamental cells. There are no obvious differences in the numbers of granule-containing processes in the DOL and POL. The varying capacity for variable tensility of the DOL and the POL may thus be due to morphologically undetectable differences in the nervous pathways controlling their tensility (i.e. in the “wiring” of the ligaments), or in the properties of their respective juxtaligamental elements: granule dimension and shape may not be good markers of functional differentiation.
