Final answer:
The initial remodeling of the intraembryonic coelom occurs during embryonic development in protostomes through a process called schizocoely.
Step-by-step explanation:
The subject of the question is Biology and the grade level is High School.
The initial remodeling of the intraembryonic coelom occurs during embryonic development in protostomes. In protostomes, the coelom forms through a process called schizocoely, where a solid mass of mesoderm splits apart and forms the hollow opening of the coelom. This process differs from deuterostomes, where the coelom forms through enterocoely. The information provided in the references explains the processes of gastrulation and the formation of the primitive gut and germ layers in embryonic development.