Rate and angle measurements for example interfaces and the evolution of intially vertical interfaces. (A) Interface angle and interface rate of length change over time shown for the example interfaces given in Fig. 2, A and B. (B) Top row: Cumulative probability distribution of interface orientation angles. Bottom row: Cumulative probability distribution of interfaces rate of length change (i.e., contraction/elongation rates). The graphs show the reverse evolution of populations of initially vertical interfaces over a time window of 15 min (n = 304 interfaces, k = 6 embryos).