Allantois

This picture was taken from the following website:
http://www.aps.uoguelph.ca/ANSC*2340/LEC3/PS23.gif

I first came across the word "allantois" in class during a lecture in the past two weeks, and the term reappeared during the reading portion of lab this week, so I decided to really find out what it means. The term is defined as "the extraembryonic membrane found in amniotes that forms off the hindgut of the embryo. It stores nitrogenous waste and, in the chick, will eventually fuse with the chorion to form the chorioallantoic membrane. It is vascularized and is formed from the splanchnopleure, a layer made up of endoderm and splanchnic lateral plate mesoderm." Essentially, the allantois is the precursor of the gut in the chick embryo. Above is a picture detailing the allantois in a sheep embryo.

The information above was taken from the following reference: http://labs.devbio.com/protected/resources/modules/LabBook/Tyler_LabManual_Complete_2010.pdf.