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Related to Blastocoel: blastopore, Blastomeres
segmentation cavity, cleavage cavity, primary body cavity, a cavity formed between the blastomeres in the embryo of an animal and filled with a liquid different in chemical composition from the surrounding medium. A blastocoel attains its greatest size towards the end of cleavage in the blastula stage. In the process of gastrulation it is gradually displaced by migrating cellular material.