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Abstract #24895 Published in IGR 11-4
Morphologic indication for proprioception in the human ciliary muscle
Flügel-Koch C; Neuhuber WL; Kaufman PL; Lütjen-Drecoll EInvestigative Ophthalmology and Visual Science 2009; 50: 5529-5536
PURPOSE: To search for proprioceptive nerve terminals in human ciliary muscle. METHODS: In 48 human donor eyes, histologic and ultrathin sections cut in different planes and wholemounts of the ciliary muscle were studied. Immunohistochemical staining with antibodies against pan-neuronal antigens and antigens reported as markers for sensory terminals in other organs was performed. RESULTS: Among the markers for proprioceptive terminals, only calretinin was present in the ciliary body. Calretinin-immunoreactive (IR) nerve terminals surrounded the posterior and reticular ciliary muscle tips and their elastic tendons. Terminals in that region contained mitochondria and neurofilaments. At the anterior tips larger terminals with numerous membrane-filled vesicles were located between the muscle fibers. The most elaborate network of calretinin-IR nerve fibers was present in the ground plate covering the circular muscle portion. Here calretinin-IR neurons with morphologic features of mechanoreception were present. Within the circular muscle portion numerous calretinin-IR ganglion cells were found. Their processes were connected to the calretinin-IR network but also surrounded ciliary muscle cells and NADPH-diaphorase-positive ganglion cells. CONCLUSIONS: These morphologic findings indicate that there are proprioreceptors in the ciliary muscle that morphologically and presumably functionally differ at different locations. At the posterior muscle tips, the receptors could measure stretch of the tendons, whereas the large receptor organs located at the anterior muscle tips morphologically resemble mechanoreceptors measuring shear stress. The presence of the numerous intrinsic nerve cells indicates that contraction of the circular muscle portion can be modulated locally via a self-contained reflex arc.
Institute of Anatomy II, University of Erlangen-Nürnberg, Universitätsstrasse 19, 91054 Erlangen, Germany. cassandra.fluegel-koch@anatomie2.med.uni-erlangen.de
Classification:
2.9 Ciliary body (Part of: 2 Anatomical structures in glaucoma)