Intermediate Mesoderm - Kidney Development Flashcards
1
Q
What are the 3 main structures that form throughout kidney development?
A
- Pronephros - develops first, very anteriorly (in the throat region)
- Mesenephros - Develops as the pronephros degenerates, made from the wolfian duct
- Metanephros - the final mammalian kidney, induced by the ureteric bud, branches for form the nephric duct
2
Q
What is the function of the pronephros? (3)
A
- in fish and amphibians it is key for osmoregulation
- induces development of later kidneys for all species
- Will degenerate in all amniotes
3
Q
What are the functions of the mesenephros?
A
- in fish and amphibians this is the adult kidney
- contains thousands of linear arrays of nephrons - In amniotes this induces later kidney development
- contains 20-40 linear arrays of nephrons
- function varies among amniotes
4
Q
What is the timing of human kidney development?
know this well
A
- in the early 4th week pronephroi begin developing
- late in the 4th week mesonephroi appear
- in the 5th week metanephroi (permanent kidneys) begin developing
5
Q
Where does reciprocal induction occur?
A
The ureteric bud (an epithelial branch) and the metanephrogenic mesenchyme
- cap condensate as ~20 cells
- ureteric bud fuses with epithelializing nodule to form a continuous tube
- induced mesenchyme expresses E-cadherin
- changes from comma shape to S shape
6
Q
When does branching occur?
A
The 32nd week
7
Q
What is bud growth dependent on?
A
GDNF - induces ureteric bud to form, expressed posteriorly by the metanephrogenic mesenchyme
- dependent on its receptor Ret on the nephric duct
8
Q
How is Wnt involved in kidney development? (3 wnts)
A
- Wnt9b - found at the stalk of the uteric bud, induces the mesenchyme to condense around it
- Wnt11 - expressed at the tips and initiates branching
- Wnt4 - an autocrine signal by the mesenchyme to become epithelial and form the nephron tube
9
Q
Where is the ureter from?
A
Intermediate mesoderm
10
Q
Where is the urethra from?
A
Endoderm
