Day 1

Major Growth Developments

•18 hours: The alimentary tract appears.

•19 hours: The brain crease begins to form.

•20 hours: Somites appear.

•21 hours: The brain and nervous system begin to form.

•22 hours: The head fold begins to form.

•23 hours: Blood islands appear.

•24 hours: The eyes begin to form.

Information & Image from the University of Illinois webpage: http://chickscope.beckman.uiuc.edu/explore/embryology/