Coverslip setting for nanoimaging of sarcomeres on the LV surface in an open-chest mouse. A coverslip set on a metal ring (denoted by Ring; diameter, 12 mm) was gently placed on the LV surface of the heart (see Materials and methods). Animal head position is to the left. The LVP change caused by this procedure is <5% (as in Kobirumaki-Shimozawa et al., 2016). The coverslip and catheter (inserted into the left ventricle via the apex) are indicated by white arrows, and one of four glued areas (yellow circles; diameter, ∼1 mm; ∼2 mm apart) is indicated by the yellow arrow. An observation area between glued areas (dotted white circle; diameter, ∼2 mm) is likewise indicated by a white arrow. Scale bar, 2 mm.