I found this site that shows a map of candling eggs from day 1 to last day. It shows what should be inside the egg at each day. It covers chicken eggs and a few other birds. I dont know if this link as been posted before or not but i found it to be helpful.
www.eggincubator.biz/Embryonic-Development-Process.html
www.eggincubator.biz/Embryonic-Development-Process.html