Proposed model for myosin filament evanescence during reversible length adaptation process. For illustration purposes, there are two and three contractile units in series in the muscle cell adapted to 0.75 and 1.5 reference length (L_ref), respectively (see text for description of the model of a contractile unit). Smooth muscle adapted to a shorter length (0.75 L_ref) contains higher concentrations of monomers, dimers, and tetramers in both folded and straightened conformations outside of the contractile units compared with the one adapted to a longer length (1.5 L_ref), which contains more filamentous myosin. Nonmuscle myosin intermediates are not shown, as they do not participate in the adaptation process. Dotted lines highlight a contractile unit. Adapted from Chitano et al. (2017) and Kuo et al., (2003).