K12 Week 4

Week 4

In week four of embryo development organs begin to form within the embryo and surface features begin to form.

Embryo at 4 weeks (Carnegie stage 13)

On the embryo surface limb buds and special sensoryregions on and near the embryo head appear.
Sensory placodes will form parts of the ear, eye and nose.
Limb buds first form from 2 layers of the embryo are the "paddle-like" projections from the body. The arms appear before the legs.
This period of organ development continues to 8 weeks of development.
Folding of the embryo continues and the earliest functioning organ is the heart.
Other systems such as the blood vessels, gut and nervous system are beginning to all take shape.

Question: Do all animals have eyes, ears and noses?

Cite this page: Hill, M.A. (2024, April 23) Embryology K12 Week 4. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/K12_Week_4