Proprioception by the Coxo-Basal Chordotonal Organ, Cb, in Legs of the Crab, Carcinus Maenas
Journal of Experimental Biology 42: 285-297
ISSN/ISBN: 0022-0949 PMID: 14323766 Accession: 025308104
The CB receptor organ is stretched by extension of the coxo-basal joint (i.e. depression of the leg), and relaxes during flexion (limb elevation). Afferent impulses were recorded extracellularly from whole CB nerves and fibers isolated from it, during passive movement of the joint, with CB in situ, and while stretching and releasing the excised receptor. Unidirectional movement and position fibers were found for both directions of joint movement, or stretch and release of the CB strand. Fibers intermediate between true movement and position fibers, and phasic movement or "acceleration" fibers were also observed. Since the scolopidia of CB are isodynal, with only ciliary type distal processes (Whitear, 1962), the simple hypothesis that the ciliary cell responds solely to receptor strand relaxation[long dash]and the paraciliary cell to stretch[long dash]is now untenable. Alternative hypotheses, and the function of CB, are discussed.