ABSTRACT
The brachial ligaments of the comatulid crinoids Antedon bifida and Decametra sp. are mainly composed of densely packed typical collagen fibrils as well as slender, about 10 nm wide fibrils, which may also be collagenous. Further constituents of the ligaments are fibroblasts and abundant cellular processes which presumably originate from the juxta-ligamental cells. These granulated cells occur at the border zone between ligament and ossicle and can be divided into several categories: a) small and large cells and b) cells with roundish electron dense granules 100 nm in diameter and cells with oval granules 180 nm in their long diameter. Although all these cells are assumed to be of neurosecretory nature innervating the ligament, only one population stains with chrome-haematoxylin and gives a positive immunoreactivity to somatostatin. The findings are discussed under the assumption that the brachial ligaments represent a mutable connective tissue.
