6. Development of the Gut Tube and Respiratory System: Key Processes and Signaling Pathways

Forming the endoderm

through a process called gastrulation

Through coordinated MET and cavitation

How does the intestinal lumen form?

Cavitation

small pockets of lumen eventually coalesce to form a single multicellular lumen

segmentation

The A-P patterning of the gut tube results in ________

Foregut

(Wnt antagonists) --> (Hhex/Sox2)

- Thyroid, Esophagus, Lung, Liver, Billary tree, Stomach, Pancreas

Midgut

(Pdx-1)

Small intestine

Hindgut

(Wnt/FGF4/BMP) --> (Cdx)

Colon

looping

The gut tube undergoes "________" in response to asymmetric Nodal signaling

liver and pancreas

The ______ and ______ bud off the gut tube on OPPOSING SIDES due to GUT TUBE LOOPING

Crosstalk

occurs between the mesoderm and endoderm to properly specify endodermal organs

vasculature

is adjacent to the gut and is a prime source of ligands for gut tube patterning and is the triggering factor for "budding-off" events

endothelium

The vasculature (____________) is important for proper differentiation of the liver and its budding-off the gut tube

FGF and BMP, hepatocyte, stratified epithelium, endothelial cells

Differentiation of liver and budding off gut tube:

- ______ and ______ from the heart mesoderm help specify liver cell fate

- Presumptive liver cells express ______ specific genes and reorganize into a "_______ _______"

- The underlying _______ ______ promote further differentiation and guide liver budding off the gut tube

trachea, lungs

The _____ buds of the foregut, followed by the ______ buds

mesenchyme

process of respiratory budding off the foregut is mediated by surrounding ___________ and its dorsal ventral patterning and positioning

Squamous esophageal epithelia

Dorsal =

Mesenchyme + Barx1 ------> forms ________ ________ ________

(sFRPs BLOCK Wnt)

Ciliated respiratory epithelia

Ventral =

Mesenchyme -------> forms _________ ______ _____

(Wnt signaling)

nodal signaling

The lung buds bifurcate in a predictable manner, the pattern dictated by _________ _____

surrounding mesenchyme, FGF10

Lung branching requires ________ ________ (and the ______ it produces)