How heart valves form in the embryo

In the developing embryo, the heart starts off as a simple straight tube that pumps blood inefficiently. As the embryo grows, the heart twists and grows and morphs into a four-chambered organ with intricate cardiac structures. Some of the most important cardiac structures are the heart valves, which prevent blood from flowing backwards through the heart chambers. How do heart valves form? And to what extent do mechanical forces caused by heartbeat and blood flow help sculpt the valves? Using the zebrafish as a model organism, the Chow lab has previously shown that mechanical forces caused by heartbeat and blood flow are essential for transforming the round cellular cushions between heart chambers into thin valve leaflets that open and close upon heartbeat. This project aims to determine how mechanical forces alter valve cell-cell adhesion and polarity during this transformation process.