[Gladwin]

I wish there were some pictures posted somewhere of these embryos. It would clear up a lot.

http://www.ulb.ac.be/sciences/biodic/EImOiseau0002.html

Which are chicken embryo pictures. Most of the tissues don't appear differentiated. At 72 hours, you can see the spine and head starting to form, at most.

[AndrewC]

Which are chicken embryo pictures.

Nice pix, but quite incomplete. Here is one more to provide a more complete data set.

The "three-minute" chicken embryo