Embryonic Development: 3rd Week

What is the primary purpose of the formation of the mesoderm during gastrulation?

What is the significance of the notochord in embryonic development?

What occurs to the neural plate during the formation of the neural tube?

How do neural crest cells differ from other cells in development?

What initiates the formation of Hensen's knot?

Where does the notochord process invaginate from during its formation?

What happens to the margins of the neural plate during its transformation into the neural tube?

Which structure persists in limiting the notochord's separation of ectoderm and endoderm?

Embryonic Development: 3rd Week

The bilaminar embryonic disc transforms into a trilaminar disc through gastrulation, involving the formation of the mesoderm layer between the ectoderm and endoderm.

Mesoderm Formation

Mesoderm forms through primitive streak cells migrating between the ectoderm and endoderm.
These cells migrate along the midline, ultimately meeting in front of the prochordal plate.

Notochord Formation

The notochord is a temporary supporting structure.
It forms from a thickened area called Hensen's knot at the cephalic end of the primitive streak, which invaginates to form the notochordal process.
The notochordal process extends anteriorly, forming a cord of cells.
It eventually arises between the ectoderm and endoderm, except in the prochordal and cecal plate regions.
The notochord provides support and induces the formation of CNS.

Neural Tube Formation

The neural plate thickens at the cephalic end of the embryo due to the notochord and adjacent mesoderm's influence.
The neural plate invaginates to form the neural groove, with neural folds rising on each side.
The folds merge to form the neural tube, separated from the ectoderm, eventually giving rise to the brain and spinal cord.
Neural crest cells differentiate at the neural plate's crest during folding and migrate into mesoderm.
Neural crest cells are ectodermal in origin but mesodermal in behavior.

This quiz explores the intricate details of embryonic development during the third week. Focus areas include the transformation of the bilaminar disc into the trilaminar disc, the formation of the mesoderm, the notochord's role, and the beginnings of neural tube formation. Test your understanding of these critical processes in embryology.