In 2015 Illinois will again process all appointment renewals electronically through the National Insurance Producer Registry (NIPR). 1  Appointment renewal date is November 1, 2015. 2  Appointment renewals will be electronically processed through NIPR.
myofibril - one of many contractile filaments that make up a striated muscle fiber. myofibrilla, sarcostyle. sarcoplasm - the cytoplasm of a striated muscle fiber. striated muscle cell, striated muscle fiber - an elongated contractile cell in striated muscle tissue.
Myofibrils contract because of the sliding action of two filamentous cytoskeletal proteins, called actin and myosin: 1  Actin filaments, or thin filaments, consist of two strands of actin wound around each other. 2  Myosin filaments, or thick filaments, contain groups of myosin.