This video shows a group of cells undergoing gravitational rotation. Fertilization was at "zero." How synchronous are the cells? Why would the cells rotate at different times or not at all? How would you graph this rotation? (e.g., number of cells rotating versus time? Could you determine the rate of one cell by estimating the degrees of ration versus time?). I grabbed one video frame every 30 sec and set the replay it back at 10 frames per sec. The replay rate depends upon your internet connection and computer.