Organogenesis 1

Question 1

What are the building blocks of the kidney?

Answer 1

• nephron
• collecting duct

Question 2

what is the precursor to the collecting duct?

Answer 2

uteric bud

Question 3

What is the precursor to the nephrons?

Answer 3

metanephric mesenchyme

Question 4

Describe the structure of the kidney briefly

Answer 4

• glomerulus
• loop of Henle
• collecting duct

Question 5

what germ layer forms the kidney?

Answer 5

mesoderm

Question 6

what part of the mesorderm forms the kidney and gonads?

Answer 6

intermediate mesoderm

Question 7

Describe the structure of the mesoderm

Answer 7

• neural tube in the middle
• further out is the paraxial mesoderm
• the intermediate mesoderm
• further out is the lateral plate mesoderm

Question 8

what are the signals that determine early kidney development?

Answer 8

• Lim-1
• Pax-2
• Pax-8

Question 9

what is the first indication that kidney cells are different from surrounding cells?

Answer 9

expression of
- Lim-1
- Pax-2
- Pax-8

Question 10

What induces the expression of Lim-1, Pax-2 and Pax-8?

Answer 10

• signals from the paraxial mesoderm (paracrine)
• signals from the lateral mesoderm (paracrine)

Question 11

what is the signal to the intermediate mesoderm from the lateral mesoderm?

Answer 11

• Bone morphogenetic protein 2 (BMP2)
• morphogen
• kidney tissue indices at medium BMP2 activity

Question 12

what precursor tissues form the whole kidney?

Answer 12

• ureteric bud (UB) (collecting ducts)
• metanephric mesenchyme (MM) (nephrons)

Question 13

What is reciprocal induction?

Answer 13

a two way conversation between two different populations of cells

Question 14

what happens if two groups of cells that usually use reciprocal induction are grown in isolation?

Answer 14

• they may have a mis match in ratio of cells
• they may have a miss match in coordination

Question 15

How was it determined that the UB and MM used reciprocal induction?

Answer 15

• cultured sepperately
• both cultures died and did not develop

Question 16

What happens of the UB and MM are cultures together?

Answer 16

• UB branches
• nephrons form - mesenchymal to epithelial transition (MET)

Question 17

What signal causes outgrowth of the UB?

Answer 17

glial cell line-derived neurotrophic factor (GDNF) - active in MM

Question 18

What the receptor for glial cell line-derived neurotrophic factor (GDNF)?

Answer 18

Ret - expressed in nephrite ducts and ureteric branches

Question 19

explain the role of GDNF signalling

Answer 19

• GDNF induced UB to grow into MM
• signalling induced further branching to produce a ureteric tree

Question 20

Explain how we know that GDNF is the signal

Answer 20

• necessary for budding and branching
• sufficient for budding and branching

Question 21

what is the role of Ret in UB branching?

Answer 21

• branching needs Ret
• Ret alters cells to promote branching

Question 22

What will happen if there is Ret++ cells and Ret+++ cells?

Answer 22

• relative levels of Ret determines branching population
• more Ret = stranger branching activity

Question 23

Describe the process of UB branching

Answer 23

• UB swells and bifurcates
• forms two new branches
• branch extends and bifurcates in reiterative process

Question 24

What is the role of proliferation in branching?

Answer 24

• more proliferation at tip than branch
• differential cell proliferation driven my Ret/GDNF signalling

Question 25

What is the role of cell arrangement in branching?

Answer 25

• Ret signalling mediates rearrangement of epithelial cells before budding

Question 26

What is the role of the ECM in branching?

Answer 26

• collagen 18 only expressed in the trunk and not the tip of the UB
• acts like a corset and prevents branching of the trunk