Development Animation - Week 3

From Embryology
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Week3_folding icon.jpg</wikiflv> This animation shows folding of the embryonic disc beginning week 3 of development.

Embryonic disc (midline section) shown to the left and early placenta to the right. The embryonic disc dorsal (ectoderm) top and ventral (endoderm) bottom. Cranial end of disc to the left and caudal end of disc to the right.

Note also the early cardiac region shown at the cranial end of disc and the allantois at the caudal end of disc extending into the connecting stalk.

Folding of the embryonic disc

  1. brings the cardiac region and allantois ventrally
  2. brings the buccopharyngeal membrane, cloacal membrane and connecting stalk ventrally
  3. encloses the embryo in amniotic cavity
  4. narrows the connection between yolk sac and midgut of the gastrointestinal tract to a channel, the yolk stalk or vitelline duct
  • blue - epiblast layer of amniotic cavity
  • yellow - endoderm layer of the yolk sac and gastrointestinal tract
  • red - outside embryo extraembryonic mesoderm and inside embryo mesoderm


Compare this sectional view of folding with the Amniotic Cavity view, filling the amnion and yolk cavities.

Amnion 001 icon.jpg

Quicktime version





Source: UNSW Embryology Thanks to the late Prof William Larsen for allowing permission to use animations based on images from his textbook. (More? movie technical information)

Links: Movies Page | Category:Movies



Cite this page: Hill, M.A. (2024, March 28) Embryology Development Animation - Week 3. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Development_Animation_-_Week_3

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© Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G