Human Embryology and Developmental Biology – Guest Lecture Development
of the Urogenital system (15-03-2018)
Michiel Schreuder
Urogenital development:
They are connected through their development, but not through their function in the
end.
If something is wrong in the urinary and the genital tract, you know that something
went wrong during very early development, because by then these systems are
connected.
Development of the urinary tract:
Kidney function:
- Metabolic balance
Clearance:
- Water
- Waste products
Erythropoietin (EPO), is produced in the kidney
Renin-Angiotensin system, regulates the blood pressure.
Functioning units of the kidneys:
- Nephron
o Glomerulus filtration of blood
o Tubular system makes sure that balance is present, takes up and
secretes nutrients.
Initially, three kidneys develop in mammals, but only the third one differentiates into
the fully functioning kidney
Pronephros – degenerates
Mesonephros – develops but not fully
Metanephos (metanephric mesenchym) – fully developing kidney, interaction with
nephric duct and uteric bud.
If the metanephros and the nephric duct do not interact, you will not get a fully grown
kidney.
Nephrogenesis:
A lot of factors are involved in formation of the kidney, if these do not interact, no
kidney will be formed. Nephrogenesis means, formation of the nephrons.
Nephrogenesis – branching morphogenesis:
Main stem – ureteric bud, invades the mesenchym and out of the tip, more and more
branching occur, until a fully grown kidney is formed.
Ureteric bud is surrounded by mesenchym, at the end of the ureteric bud branching
keeps happening.
, In all mammals the kidney develops in the same manner.
Urine has to flow back to the ureteric bud, which will develop into the collecting
system with the collecting ducts in order to collect the urine and drain it down to the
bladder.
In a fully developed nephron:
- The glomerulus + proximal part of the tubular system: based on mesenchym
- Collecting duct + distal part of the tubular system: based on the ureteric bud.
Genetic variations have an impact on renal development:
Specific genotyping leads to a different size of kidneys more or less nephrons
formed.
The most medullary branches will form the new nephrons and start formation of the
glomerulus. The branches branch out to the cortex, where the final nephrons are
formed.
Before birth, all the nephrons you need for your entire life are formed. During lifetime
the nephrons grow, no new nephrons will be formed.
Urinary tract development – zebra fish:
Zebra fish is used, because this fish is easily produced, and they don’t need much
taking care off. They come from a very polluted river in India and they survived,
which meant that they did not need much, in order to survive.
What makes kidneys from fish unique? – Unique kidney plasticity
- The adult zebrafish kidney undergoes nephrogenesis throughout life and after
injury (regeneration)
- Sharks are capable of living in both salt and fresh water by adjusting urea
excretion.
Mammals do not have these kinds of mechanisms to form new nephrons/kidneys.
Taking in too much salt, leads to a high blood pressure for mammals, because our
kidneys cannot handle this.
Development of the kidney starts caudally – kidneys have to ascend.
Je hebt eerst de bijnieren (adrenals) en vervolgens verplaatsen de nieren naar de
locatie van de bijnieren.
Congenital anomalies of the kidney and urinary tract: CAKUT.
Locational problems:
- Ectopic kidney: normally, the kidney develops and ascends and makes up
new arteries every time, causing the other ones to involute and disappear.
When this involution does not happen you end up with a second/third
artery/vein, etc. that is connected to the kidney this causes no problems for
the person itself, only for the surgeon when a kidney transplantation is
necessary.
of the Urogenital system (15-03-2018)
Michiel Schreuder
Urogenital development:
They are connected through their development, but not through their function in the
end.
If something is wrong in the urinary and the genital tract, you know that something
went wrong during very early development, because by then these systems are
connected.
Development of the urinary tract:
Kidney function:
- Metabolic balance
Clearance:
- Water
- Waste products
Erythropoietin (EPO), is produced in the kidney
Renin-Angiotensin system, regulates the blood pressure.
Functioning units of the kidneys:
- Nephron
o Glomerulus filtration of blood
o Tubular system makes sure that balance is present, takes up and
secretes nutrients.
Initially, three kidneys develop in mammals, but only the third one differentiates into
the fully functioning kidney
Pronephros – degenerates
Mesonephros – develops but not fully
Metanephos (metanephric mesenchym) – fully developing kidney, interaction with
nephric duct and uteric bud.
If the metanephros and the nephric duct do not interact, you will not get a fully grown
kidney.
Nephrogenesis:
A lot of factors are involved in formation of the kidney, if these do not interact, no
kidney will be formed. Nephrogenesis means, formation of the nephrons.
Nephrogenesis – branching morphogenesis:
Main stem – ureteric bud, invades the mesenchym and out of the tip, more and more
branching occur, until a fully grown kidney is formed.
Ureteric bud is surrounded by mesenchym, at the end of the ureteric bud branching
keeps happening.
, In all mammals the kidney develops in the same manner.
Urine has to flow back to the ureteric bud, which will develop into the collecting
system with the collecting ducts in order to collect the urine and drain it down to the
bladder.
In a fully developed nephron:
- The glomerulus + proximal part of the tubular system: based on mesenchym
- Collecting duct + distal part of the tubular system: based on the ureteric bud.
Genetic variations have an impact on renal development:
Specific genotyping leads to a different size of kidneys more or less nephrons
formed.
The most medullary branches will form the new nephrons and start formation of the
glomerulus. The branches branch out to the cortex, where the final nephrons are
formed.
Before birth, all the nephrons you need for your entire life are formed. During lifetime
the nephrons grow, no new nephrons will be formed.
Urinary tract development – zebra fish:
Zebra fish is used, because this fish is easily produced, and they don’t need much
taking care off. They come from a very polluted river in India and they survived,
which meant that they did not need much, in order to survive.
What makes kidneys from fish unique? – Unique kidney plasticity
- The adult zebrafish kidney undergoes nephrogenesis throughout life and after
injury (regeneration)
- Sharks are capable of living in both salt and fresh water by adjusting urea
excretion.
Mammals do not have these kinds of mechanisms to form new nephrons/kidneys.
Taking in too much salt, leads to a high blood pressure for mammals, because our
kidneys cannot handle this.
Development of the kidney starts caudally – kidneys have to ascend.
Je hebt eerst de bijnieren (adrenals) en vervolgens verplaatsen de nieren naar de
locatie van de bijnieren.
Congenital anomalies of the kidney and urinary tract: CAKUT.
Locational problems:
- Ectopic kidney: normally, the kidney develops and ascends and makes up
new arteries every time, causing the other ones to involute and disappear.
When this involution does not happen you end up with a second/third
artery/vein, etc. that is connected to the kidney this causes no problems for
the person itself, only for the surgeon when a kidney transplantation is
necessary.
