Studies on the Development of the Foregut in the Chick Blastoderm: 1. The Presumptive Foregut Area

A brief morphological account is given of the changes which take place in the endoderm during the first stages of foregut formation. The period of development concerned is from the stage of the primitive streak to that of the embryo with about ten pairs of somites. Experiments are described in which the endoderm of chick blastoderms grown in vitro was marked with carbon particles. By this means the presumptive foregut area was found to lie around the anterior end of the primitive streak in the long streak stage, and around the head process and anterior end of the primitive streak at a slightly later stage of development.