During which stage of zygote formation do cells migrate to create a cavity?

During the blastula stage of zygote formation, cells migrate to create a cavity known as the blastocoel. This stage follows the morula stage, which consists of a solid ball of cells formed after several rounds of cleavage. In the blastula stage, the cells begin to reorganize and migrate to form a hollow structure, signifying the start of further development.

The formation of the cavity is crucial as it marks the transition from a solid mass of cells to a more complex structure that will eventually lead to the gastrulation phase, where the three germ layers—ectoderm, mesoderm, and endoderm—are established. This process sets the foundation for the body's structure and organ systems.

In contrast, the morula stage involves a solid ball of cells without a cavity, while the zygote stage refers to the initial fertilized egg that has not yet undergone cleavage or cell migration. Gastrulation, while important for subsequent development, occurs after the formation of the blastula and is characterized by the movements that will form the different tissue layers, not the creation of a cavity itself.