11. Kidney embryology Flashcards
What are the two embryonic ducts in a developing foetus
During the initial development, the foetus will have both wolffian/mesonepheric (male) and mullerian/paramesonepheric (female) ducts
How does the presence of the embryonic ducts change as development continues?
If the foetus is genetically predisposed to become a female then the wolffian/mesonepheric ducts will degenerate and the mullerian duct will remain and continue to develop as an oviduct (a small part of the wolffian duct remains to form the uretic bud)
If the foetus is genetically predisposed to become a male then the mullerian/paramesonepharic ducts will degenerate and the wolffian ducts will remain and continue to develop as the ureter
How many kidneys are there during development?
There are three embryonic kidneys
The wolffian and mullerian are the first two and these are non-functional and quickly degenerate
The third is the metanephric kidney and this is what remains
Where does the metanephric kidney develop from?
BE CAREFUL: The metenephric kidney develops from the mesonepheric duct
REMEMBER THAT ALTHOUGH IT DEVELOPS FROM THE MESONEPHRIC (WOLFFIAN) DUCT, THE MESONEPHRIC KIDNEY IS AN EMBRYOLOGICAL NON-FUNCTIONAL KIDNEY - don’t get confused by this
How is the metanephric kidney formed?
Formed from two embryonic structures - the uteric bud and the mesenchyme
The uteric bud grows out of the side of the mesonephric duct (remains of this) and comes into contact with the mesenchyme
When these two come into contact with each other, the kidneys start to develop
The uteric bud starts to develop into the ureter
What structures of the kidney form from the uteric bud?
Essentially forms the 'collecting system' of the kidney: Ureter Renal pelvis Major and minor calyces Collecting tubules
What structures of the kidney form from the metanepheric bud (the mesenchyme)?
Essentially forms the 'excretory system' of the kidney i.e. the nephron: Renal glomerulus and capillaries Bowman's capsule Proximal convoluted tubule Loop of Henle Distal convoluted tubule
Describe the development of the metanephric bud
In order to develop all the structure of the nephron, the metanephric bud will bifurcate to form many tubules - will bifurcate many times to form numerous tubules
Where in the body do the kidneys develop?
Embryonic development of the kidney occurs low down in the sacral region - S1
Where do the kidneys move to during development?
The kidneys ascend to the lumbar region - T12
Mechanism for this ascension is not fully known
What is it called if a kidney fails to ascend?
This is known as an ectopic kidney
What is the role of the renal arteries as the kidney ascends?
As the kidney ascends, the renal arteries degenerate and reform higher up and then degenerate again and reform even higher up
This process continues until the kidney moves up to it’s resting place at T12
What is kidney agenesis?
This is a failure of the kidneys to form and develop
Why might kidney agenesis occur?
Explain this
Due to a failure of the development of the uteric bud - the bud will then not come into contact with teh mesenchyme and so there will not be a development fo the kidney - can be unilateral or bilateral - if unilateral then the other kidney will continue to function but if bilateral then the person cannot survive
OR due to a failure of the development of the renal arteries during the ascent of the kidneys
What might happen if the uteric bud pathologically splits into two?
This means that the ureter will split into two
May result in the formation of multiple kidneys e.g. two on one side
