Embryology of the urinary system Flashcards
1
Q
How many kidney systems form during development?
A
- 3 separate systems develop sequentially
- Disappearance of one system marks onset of development of next stage
- Develop from intermediate mesoderm
2
Q
Where does the pronephros develop?
A
- 1st appears in the cervical region
- Pronephros is 1st kidney system
3
Q
Which part of the embryo forms the bladder?
A
- Endoderm
4
Q
What are the names of the different kidney systems that form during embryonic development?
A
- 1st attempt called pronephros
- Then mesonephros
- Then metanephros - gives rise to functioning kidney
5
Q
What is the pronephros?
A
- First kidney system, never functions in humans
- Forms pronephric duct - important for next stage of kidney system
6
Q
Where does the pronephric duct extend from?
A
- Cervical region to cloaca
7
Q
What is the mesonephros?
A
- Mesonephric tubules develop caudal to pronephric region
- Mesonephric duct = embryonic kidney
- No water conserving function
8
Q
Why do we need to know about the mesonephros?
A
- Mesonephric duct has important role in development of reproductive system in male
- Sprouts ureteric bud which induces development of definitive kidney
9
Q
What is the metanephros?
A
- Undifferentiated intermediate mesoderm, caudal to mesonephros
- Ureteric bud induces development of true kidney, metanephros in this tissue
10
Q
How is the definitive kidney formed?
A
- Ureteric bud contacts metanephric blastema
- Sends out growth factors
- Bud expands and branches, becomes differentiated to form kidney as we know it
- Ureteric bud becomes collecting system
- Undifferentiated tissue of metanephric blastema becomes nephrons
11
Q
How does the renal functional unit develop?
A
- Ureteric bud drives development of definitive kidney
- Collecting system is derived from ureteric bud
- Excretory component is derived from intermediate mesoderm under influence of ureteric bud
12
Q
Outline the ascent of the kidney
A
- Metanephric kidney first appears in pelvic region
- Undergoes an apparent caudal to cranial shift, crossing arterial fork formed by vessels returning blood from foetus to placenta
- Kidney swaps positions with gonads
13
Q
What happens to blood supply of the kidneys as they ascend?
A
- They pick up blood supply from aorta
- These vessels degenerate as kidneys continue their ascent and move higher up in the body
- By week 9 only supplemental arteries should remain
14
Q
What can go wrong with the development of the kidneys?
A
- Ureteric bud fails to interact with intermediate mesoderm - causes renal agenesis
- Migration goes awry
- Duplication defects
- Ectopic ureter
- Cystic disease
15
Q
What structural abnormalities can occur in the kidneys that are related to migration?
A
- Pelvic kidney - kidney never ascends to underneath adrenal glands
- Horseshoe kidney - poles of kidney fuse together so kidneys get caught on inferior mesenteric artery and can’t ascend
