What are the key stages of endodermal differentiation?
The differentiation of the endoderm into various organ systems involves several stages:
Specification: Initially, the endodermal cells are specified by signaling pathways such as Nodal, Wnt, and FGF. These pathways ensure the cells are committed to an endodermal fate. Patterning: The endoderm is patterned along the anterior-posterior axis, determining future organ locations. Retinoic acid and other signaling molecules play a crucial role in this process. Organogenesis: The patterned endoderm undergoes further differentiation to form organs. For example, the foregut gives rise to the lungs and thyroid, while the midgut and hindgut form the intestines and urinary bladder.
