K12 Week 3

Week 3

In the third week of development the blastocyst has now burrowed into the wall of the uterus and cells on the outside are beginning to form early parts of the placenta.

A week 3 Human Embryo The clump of cells inside the blastocyst has also begun to change and now looks like 2 discs of cells. It looks like 2 dinner plates stacked on top of each other. The picture shows looks at this stack from the top. Cell from the top plate move down to form a new layer. The embryo now looks like stacked 3 dinner plates.

We use stages as a way of measuring changes in the embryo. Stages are like different years at school: each year something new will occur, each stage something new will happen. Stages are also a way of comparing changes that occur in different animals. (More?) (If all animals have the same stages why do they end up looking different?)

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Cite this page: Hill, M.A. (2024, April 19) Embryology K12 Week 3. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/K12_Week_3

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