Figure 5.

Trajectories of cardiomyocyte movement during heart tube elongation. Images depict the initial frame of time-lapses tracking heart tube elongation in embryos expressing Tg(myl7:egfp) (green). Dorsal views, anterior up. Arrows indicate paths traveled by individual cardiomyocytes as they leave these starting positions and proceed with heart tube elongation. (A) In wild-type embryos, patterns of cell movement exhibit left-right asymmetry: although all tracked cells move toward the anterior and left, the cells on the left (yellow tracks) move considerably faster than the cells in the center (white tracks) or the cells on the right (red tracks). (B) In ntl morphants, the left-right asymmetry of cell behavior is lost: all cells move toward the anterior, but not toward the left, and the velocity of the cells on the left (yellow tracks) is similar to that of the cells on the right (red tracks). (C) Similarly, in spaw morphants, cells move toward the anterior, rather than toward the left. However, cells move more slowly in spaw morphants, compared to the velocities observed in wild-type embryos or ntl morphants. Adapted from Lenhart et al. (2013).