Branching morphogenesis Flashcards
(27 cards)
What is branching morphogenesis fundamental for
Tissue formation with large surface areas for fluid/gas exchange
What are two organs which use branching morphogenesis
Lungs and Kidneys
What two tissue layers are used in branching morphogenesis
Epithelium and mesenchyme
What determines the formation of lungs and kidneys
hox gene expression along A-P axis
What Hox genes determine kidney formation
Hoxa11/c11/d11
After having hox11 fate in the intermediate mesoderm, what induces kidney formation
Bmps from lateral plate mesoderm and paraxial mesoderm
What Tfs mark kidney formation in intermediate mesoderm
Pax2, Pax8 and Lim1
What 2 cell types does intermediate mesoderm give rise to
Metanephric mesenchyme (MM) and ureteric bud epithelium (UBE)
Which TF directly induces MM and UBE formation
Pax2
how is the anterior intermediate mesoderm patterned
High levels of FGF9 and retanoic acid
Lower levels of Wnt
what does anterior intermediate mesoderm give rise to
UDE
How is posterior intermediate mesoderm patterned
Low levels of FGF9 and retanoic acid
High levels of Wnt
What does posterior intermediate mesoderm give rise to
Metanephric mesenchyme
What structure is in the Intermediate mesoderm before MM and UDE induction
nephrogenic cords
How do the nephrogenic cords develop
Pronephros - poor filtration function, degrade to form..
Mesonephros - creation of mesonephric duct which has better filtration
Metanephric- forms when UDE induced, collecting ducts of the kidneys
Formation of metanephros
Ureteric bud forms off nephric duct
undergoes branching morphogenesis
nephrons form and join to growing ureteric bud
Branching morphogenesis process in kidneys
-ureteric bud is surrounded by MM
-MM secretes GDNF which causes ureteric bud cell proliferation
-leading edge tip cell stops proliferating after time, causing bud to flatten
-lateral tip cells don’t stop, creating 2 new tips
Process repeats
How does GDNF act in UDE cells
UDE have RTK receptor Ret for GDNF
this induces Wnt11 which signals to MM cells positively to keep sending GDNF
How do nephrons form
Ureteric bud signals formation of renal vesicles
(MESENCHYMAL TO EMPITHELIAL TRANSITION)
renal vessels proliferate into S-shaped bodies which fuses with the ureteric bud and attracts endothelial capillaries
tissues that give rise to lungs
endoderm and mesoderm
What will endoderm give rise to in the lungs
Epithelial lining of trachea, larynx, bronchi, alveoli
How does the lung start forming
formation of the respiratory diverticulum which buds off the primitive gut tube
The bronchial tip then starts branching morphogenesis
what happens as branching morphogenesis starts in the lungs
Mesoderm surrounds each lung bud
How does branching morphogenesis start in the lungs
Mesenchyme cells secrete FGF10 to epithelial cells, which have FGFR, causing receiving cell to grow towards the source. This induces Shh, Bmp4 and Sprouty signalling in the tip cell
