Movie S1

Control AVC explant
Control AVC explant cultured on collagen gel. The explant was immunostained with a mesenchymal marker (α-smooth muscle actin, SMA, magenta) and an actin cytoskeletal marker (phalloidin, green). Endocardial-derived mesenchymal cells (magenta) have migrated away from the center of the explant and invaded the collagen matrix.