Name: early blastula stage
ECAO ID: 0000260
Definition: "The embryo is composed of slightly more than 200 cells, as most blastomeres have completed an additional mitotic division after the very early blastula stage. The embryo is surrounded by a fertilization envelope. The embryo remains spherical and one cell layer thick, and the blastocoel has expanded slightly since the very early blastula stage, without increasing though the size of the embryo. The synchrony of cell divisions between animal and vegetal cell tiers, as well as within cell tiers, is becoming less pronounced. Note for euechinoid indirect developers: Molecular labeling typically indicates the presence of 16 large micromere descendants and 4 small micromeres at this stage ."
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