K12 Week 5 to 8

From Embryology

Week 5 to 8

Week 8 Embryo

This movie shows the internal organs (gastrointestinal tract and lungs).

(red) lungs

(purple) stomach

See the size and position of these organs at this early stage of development.

See also that some of the gastrointestinal tract (intestines) lie outside the embryo at this time in development.


The lungs and gastrointestinal tract do not begin to work until after birth.

Think about what this may mean if there were problems with the development of these systems.

Adult gastrointestinal tract cartoon.jpg Bronchi lungs.jpg
Adult gastrointestinal tract Adult lungs


In the fifth to eigth (5-8) week of embryo development, organs begin to form within the embryo. This period covers approximately the last stages of major embryonic development, after this time the embryo is described as a fetus.

Start by comparing at the outside (external) changes in what the embryo looks like from week 5 to week 8. What new things can you see over this period?

Even though from the outside the embryo now looks very developed, if we were to look inside the embryo's head for a brain, we would find only a very thin layer of cells surrounding a large fluid-filled space. (almost like a water-filled balloon).




Cite this page: Hill, M.A. (2019, May 26) Embryology K12 Week 5 to 8. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/K12_Week_5_to_8

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© Dr Mark Hill 2019, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G