Hypoblast

Hypoblast is a layer of cells that, during the development of an embryo, forms the endoderm. The endoderm is one of the three primary germ layers in the very early embryo. The other two layers are the ectoderm (outside layer) and mesoderm (middle layer), with the endoderm being the innermost layer.

Formation

The hypoblast is formed during the process of gastrulation. Gastrulation is a phase early in the embryonic development of most animals, during which the single-layered blastula is reorganized into a multilayered structure known as the gastrula. The hypoblast cells migrate along the inner surface of the cytotrophoblast layer, displacing the epiblast cells and forming a layer beneath them.

Function

The hypoblast contributes to the formation of the embryo and extraembryonic tissues. It forms the yolk sac, which provides nutrients to the developing embryo, and also contributes to the formation of the gut. The hypoblast also plays a role in the formation of the amnion, the membrane that surrounds and protects the embryo.

Clinical Significance

Abnormalities in the formation of the hypoblast can lead to developmental disorders. For example, an incomplete formation of the hypoblast can result in a lack of certain organs or tissues, such as the gut or yolk sac.

See Also

• Gastrulation
• Embryogenesis
• Endoderm
• Epiblast
• Cytotrophoblast

References

Hypoblast Resources
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