I-band | definition of I-band by Medical dictionary
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isotropic band a light band which, in electron micrographs, can be seen traversing skeletal muscle myofibrils. Each myofibril is made up of a series of sarcomeres in the form of a chain (see SARCOMERE and Fig. 273 ). In electron micrographs the fibrils can be seen to have dark and light bands. Each I-band is traversed by a darker Z-membrane and is made up of thin filaments of ACTIN. See MUSCLE and Fig. 225 .