K12 Week 2

Week 2

In the second week of development the dividing zygote forms a solid ball of cells and is now called a blastocyst.

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This movie shows human development between day 3 and day 6 after fertilization.

The movie finishes with the blastocyst hatching just before the beginning of week 2 in development.

Week 2 is then about this blastocyst attaching and implanting into the uterus wall.

The cells on the surface of the ball will not form part of the embryo and will go on to make the placenta and membranes that surround the embryo.
The cells on the inside form a small clump beside a fluid filled space. This small clump of cells (embryoblast) will form all the parts of the embryo.

During this second week the blastocyst will stick to the inside of the uterus and will no longer float free. This sticking process is required to allow the blastocyst to begin to get food from the mother.

Question: You start as a single cell, how many cells are you now?

Words Used

blastocyst - the name given to all the new cells formed from the first cell (the zygote).

implanting - this means to burrow into the uterus wall.

Cite this page: Hill, M.A. (2024, April 19) Embryology K12 Week 2. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/K12_Week_2

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