blastoderm

biological membrane

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June 22, 2026

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The blastoderm is the epithelial layer of cells that forms the outer covering of a blastula, which is a hollow sphere of cells produced during early embryonic development. This layer encloses a fluid-filled cavity called the blastocoel. The blastoderm undergoes significant transformation during gastrulation, a process where the cells rearrange to form the three primary germ layers: ectoderm, mesoderm, and endoderm. These germ layers are the precursors to all the tissues and organs in an adult animal.12

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blastula
…epithelial (covering) layer, called the blastoderm, enclosing a fluid-filled cavity, the blastocoel. After the blastula develops, it undergoes transition to the gastrula (q.v.), a process called gastrulation. In organisms such as mammals, the earlier morula (q.v.), a berrylike cluster of cells, develops into a somewhat different form of blastula, the…
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…epithelial (covering) layer, called the blastoderm, enclosing a fluid-filled cavity, the blastocoel. After the blastula develops, it undergoes transition to the gastrula (q.v.), a process called gastrulation. In organisms such as mammals, the earlier morula (q.v.), a berrylike cluster of cells, develops into a somewhat different form of blastula, the…
Read More

animal development
Cleavage
…of cells is called the blastoderm, and the fluid-filled cavity the blastocoel. In discoidal cleavage the cells, which do not surround the whole embryo, lie only on the animal pole; nevertheless, a blastocoel may be formed by a crevice appearing between the blastomeres and the mass of yolk. The blastomeres…
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…of cells is called the blastoderm, and the fluid-filled cavity the blastocoel. In discoidal cleavage the cells, which do not surround the whole embryo, lie only on the animal pole; nevertheless, a blastocoel may be formed by a crevice appearing between the blastomeres and the mass of yolk. The blastomeres…
Read More