Organogenesis 2 Flashcards
1
Q
Give a brief overview of nephron development
A
- MM cells condense around UB
- transform into small cysts with epithelial characteristics (renal vesicles)
- differentiation and morphogenesis. fuses with UB
- blood vessel progenitors invade and make glomerular capillaries
- nephron differentiation
2
Q
What does the signal from UB to MM do?
A
- indices mesenchymal to epithelial transition (MET)
3
Q
What signal causes the MM to undergo MET?
A
- Wnt9B (paracrine)
4
Q
Where is Wnt9B expressed in kidney development?
A
in the UB
5
Q
How is renal vesicle size measured?
A
- Wnt9B indices Wnt4 expression in the MM
- Wnt4 is autocrine and propagates mesenchymal aggregation
- Renal vesicle will grow until Wnt4 reached threshold
- at this threshold RV will then differentiate
6
Q
What are the characteristics of the epithelial cells formed by MET?
A
- tubular shape and forms a lumen
- adhesion junctions to stick together - tight junctions and desmosomes
- established apico-basal polarity
- tubes are not leaky because of tight junctions
7
Q
explain the proximal-distal axis in the nephron
A
- proximal - glomerulus
- other side of loop of henle
8
Q
give 3 examples of differentiated cell types in the nephron
A
- proximal tubes - recovery of salt, water and metabolites
- loop of henle - produces hypertonic urine
- distal tubes - K+, Na+, Ca+ regulation
9
Q
Describe the pattern formation in the renal vesicle
A
- renal vesicle - patterning is established into 3 by a morphogen secreted at the distal end
- comma-shaped - proximal end sticks out
- s-shaped
10
Q
What is Bartter syndrome?
A
- low potassium levels
- excessive urinary losses of Na+, Cl-, K+
- dysfunction in Na-K-Cl transporter in loop of henle
11
Q
Explain the structure of the mature glomerulus
A
- Bowmans capsule around the outside
- podocytes ontop of capillaries
- capillaries inside Bowmans capsule
12
Q
Explain the development of the glomerular capillaries
A
- migrating epithelial cells move into the developing glomerulus when it is s-shaped
- migrates by a chemoattractant secreted by podocyte precursors
- chemoattractant is vascular endothelial growth factor (VEGF)
13
Q
what is a chemoattractant?
A
cells move towards signal up concentration gradient
14
Q
What is a chemorepellent?
A
cells move away from a signal down the concentration gradient
15
Q
What is VEGF?
A
- vascular endothelial growth factor
- chemoattractant ssecreted my podocyte precursor cells to attract endothelial cells
