Help Resolving Conflicting Information about the Extraembryonic Mesoderm

Hi all!

I have a bit of a problem with letting things go, and this often hampers my studying! I was reading about the formation of the extra-embryonic membranes, and decided to spend some time researching the extra-embryonic mesoderm. These cells help to make the extra-embryonic coelom; however, I do not know where these extra-embryonic cells come from (epiblast or hypoblast)!

I've listed a few of the many sources I've looked at below, and one can clearly see that these different sources are providing conflicting information:
1.My textbook (Campbell 10th ed.) has stated that they are derived from the epiblast

2. Wikipedia article on "Gestational sac": "some of the migrating hypoblast cells differentiate into mesenchymal cells that fill the space between Heuser's membrane and the Trophoblast, forming the extraembryonic mesoderm".
Link: https://en.wikipedia.org/wiki/Gestational_sac

3.Wikipedia article on "epiblast": "The amnionic ectoderm and extraembryonic mesoderm also originate from the epiblast."
Link: https://en.wikipedia.org/wiki/Epiblast

4. Boundless article on the extra-embryonic coelom: "some of the migrating hypoblast cells transdifferentiate into mesenchymal cells that fill the space between Heuser's membrane and the trophoblast, forming the extraembryonic mesoderm
Link: https://www.boundless.com/physiology/textbooks/boundless-anatomy-and-physiology-textbook/human-development-and-pregnancy-28/second-week-of-development-262/development-of-the-extraembryonic-coelom-1294-393/

5. Life Maps article: "During gastrulation, the epiblast cells undergo epithelial-to-mesenchymal transition and delaminate to become the loose mesenchyme of the primitive streak".
Link: http://discovery.lifemapsc.com/in-vivo-development/epiblast/epiblast

I have also found one other forum where they stated the mesenchymal cells arose from the epiblast. Furthermore, I've come across a book that states it is derived from both the epiblast and hypoblast.

I really appreciate everyone's help on this! It's not a huge issue, but I find it very annoying that so many sources provide opposing information!

Thank you everyone!