formation comes about as a logical consequence of folding, differential growth, and relations to major vascular channels
mesenchymal interaltions vital to normal development
differentiation of numerous enzyme systems
The esophagus becomes abruptly narrowed just causal to
the last pharyngeal pouch.
Where does tracheal evagination begin?
ventrally, just caudal to the last pharyngeal pouch
Where is the origin of the trachea?
the posterior limit of the pharynx
How is the esophagus formed?
original endoderm gives rise to the epithelial lining only, inducing the surrounding mesenchyme to form the rest of the esophagus.
Early on the esophagus is occluded by
proliferation fo the epithelium, but it is cleared by cell death later.
When do the gastric glands and rugae develop?
within the first few weeks of fetal life.