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#epiboly

2 public questions tagged with this topic.

Fertilization in mammals-iv

Epiboly assists in:

Epiboly describes overgrowth and spreading of ectodermal epithelial sheets to enclose underlying embryonic structures such as mesoderm, endoderm or yolk mass. During gastrulation epibolic movement thins surface layer via radial intercalation while expanding its area, sealing embryonic blastopore or wrapping yolk syncytial layer. This enclosure creates continuous outer epithelium that later becomes epidermis and protects internalizing progenitors, ensuring proper body plan. It does not directly form neural tube, which relies on neurulation folding, but provides substrate and positioning. Failure results in exogastrulation and incomplete envelopment of vegetal hemisphere.

Ref: Solnica-Krezel & Sepich, Methods Mol Biol 2012: Epiboly as spreading epithelial morphogenetic movement enclosing embryo and yolk.

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Fertilization in mammals-iv

Epiboly during gastrulation involves:

Epiboly is a major morphogenetic movement during gastrulation where sheet-like ectodermal cells spread, flatten and thin to enclose deeper mesodermal and endodermal layers and eventually yolk. It does not involve invagination but rather radial intercalation and expansion of superficial epithelium driven by remodeling of E-cadherin contacts, actin cytoskeleton and differential adhesion. In zebrafish, amphibians and mammalian embryos epiboly helps position ectoderm externally to form epidermis and neural ectoderm. Failure of epiboly leaves involuting marginal cells uncovered, disrupting body axis formation and gastrulation closure.

Ref: Gilbert, Developmental Biology, 12th ed., Chapter 8: Gastrulation movements - epiboly, involution and convergent extension mechanisms.

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