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

Little attention has hitherto been paid to the early stages in the development of the foregut in the chick. This paper is the first of a series concerned with an investigation into how it develops during the period between the primitive streak stage and the stage of an embryo with about ten pairs of somites. The term ‘foregut’ refers throughout to the blind diverticulum extending forward into the developing head from the anterior intestinal portal. The present communication opens with a brief consideration of the gross morphological changes which take place; the rest of the paper is concerned with the location in primitive streak and head process stage blastoderms of the presumptive area from which the foregut of the ten somite embryo will develop. The following account has been compiled from the study of serial sections of twenty embryos and from the publications of Duval (1889), Adelmann (1922), and Wetzel (1929).