““The proteins create a gradient within the egg. Like sugar diffusing out of a cube in a cup of coffee, they are present at high concentration on one end of the egg, and low concentration on the other. The diffusion of a chemical through a matrix of protein can even create distinct, three-dimensional patterns-like a pool of syrup ribboning into oatmeal. Specific genes are activated at the high-concentration end versus at the low-concentration end, thereby allowing the head-tail axis to be defined, or other patterns to be formed.””
