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The original post: /r/askscience by /u/Mister___Me on 2024-12-19 17:02:23.

I'm currently studying for my embryology exam and there's one thing during I can't understand.

One of the first thing the embryo does when arriving int the uterus is nesting in the endometrium. A this point the embryo is under the simple epithelia of the endometrium.

But once the embryo turns into a foetus and start to get bigger how does this small layer contain the foetus ? There must be a point where the foetus break the epithelia to develop in the womb cavity where he has a place to grow and from where he'll be able to get out during child birth ?