Surface Strains in the Looping Embryonic Chick Heart Measured Using Optical Coherence Tomography

The heart is the first functional organ in the vertebrate embryo. In the chick embryo, the heart begins beating at Hamburger and Hamilton [1] stage 10 (approximately 35 hours of a 21-day incubation period). The initially straight heart tube bends and twists into a c-shaped tube before reaching stage 12 (approximately 48 hours incubation). This process, known as c-looping, marks one of the first visible signs of left-right asymmetry in the embryo. Incorrect looping is one cause of congenital heart defects, where significant malformations occur in roughly 1% of human live births [2]. Understanding the mechanisms that drive c-looping could lend insight into the processes causing some of these defects.