GAP-JUNCTIONS ARE FOUND BETWEEN IRIS SPHINCTER SMOOTH-MUSCLE CELLS BUT NOT IN THE CILIARY MUSCLE OF HUMAN AND MONKEY EYES

Physiological studies indicate that in primate ciliary muscle there is little or no spread of electrical activity from cell to cell. To clar ify to what extent primate intraocular smooth muscles express the stru ctural correlate of electrical coupling, the localization of gap junct ions in the ciliary and the iris sphincter muscle of human and monkey (Macaca fascicularis) eyes was analysed using electronmicroscopy and c onnexin43 immunocytochemistry. With both methods, numerous gap junctio ns were identified in the iris sphincter of both species, while no suc h junctions were observed between individual smooth muscle cells in th e ciliary muscle. Both ciliary and iris sphincter smooth muscle cells were connected by numerous adherens-type junctions. These results furt her underline that primate ciliary muscle is an atypical smooth muscle which shares many common features with striated skeletal muscle. (C) 1996 Academic Press Limited