Some made in the egg. More details to follow. Point of fertilization can determine an additional axis. Note distinction between somatic cells and germ cells is set up early and maintained throughout. By invagination .
Blastomeres move relative to one another.
40.1 for fates of each layer. There are 2 major styles of development 1. What happens is largely independent of environment. Common in protostomes 2. See Purves 15.7 2.