BIO380H5 Lecture Notes - Lecture 25: Septum Transversum, Urogenital Sinus, Cloacal Membrane
Document Summary
Digestive system forms by the lateral folding of the endodermal germ layer into a tube bound at its cephalic end by the oropharyngeal membrane and the at the caudal end by the cloacal plate. The gut is in contact with the yolk sac through the yolk stalk- and can be divided into a foregut, midgut and a hindgut. During the period of late gastrulation, initial patterning of the gut endoderm begins and the sheet of newly formed endoderm starts to form a gut tube. Initial broad patterning into anterior and posterior domains by nodal and fgf-4. Hindgut- marked by the expression of cdx-2 throughout and the late expression of pdx-1 in the midgut (separate identity) Cdx-2 acts as an upstream of a range of hox activity. Fgf-4 expressed strongly near the foregut-midgut boundary and fgf-10 is associated with the establishment of the cecum.
