Urinary System - Embryology Flashcards
what abnormality is shown here?
horseshoe kidney
What is in the adult urinary system?
Kidneys
- Nephron
- Collecting duct
- Calyces and pelvis
Ureter
Bladder
Urethra
Blood supply
what are the 3 parts of the mesoderm and what do they form?
what is shown here?
Lateral folding of embryo
(seen in cross section)
___________ mesoderm forms the Urinary and reproductive systems (GU system)
Intermediate
what process is being shown here?
______________ connecting to the yolk sac
Head and tail fold
Vitelline duct
Out pouching at the back is what is going to be the start of the urinary system and is called the allantois
(seen in midsagittal sections)
what is Allantois?
Allantois is an outpouching of endoderm at the hindgut that extends into the body stalk
what is the Cloaca?
Definition: (noun) The cloaca is the single posterior opening for a bird’s digestive, urinary and reproductive tracts and is used to expel feces and lay eggs
Allantois and cloaca:
The cloaca divides to form ______ (GI tract) and anteriorly the ________ _____.
The mesonephric duct drains into the _______ _____
The urogenital sinus later forms the ______ _______ and its caudal end forms the ________
Allantois obliterate once umbilicus forms and develops into the _______
Allantois and cloaca:
The cloaca divides to form rectum (GI tract) and anteriorly the Urogenital Sinus.
The mesonephric duct drains into the urogenital sinus
The urogenital sinus later forms the urinarybladder and its caudal end forms the urethra
Allantois obliterate once umbilicus forms and develops into the urachus
_ sets of kidneys develop sequentially during nephrogenesis
3
(nephrogenesis - describes the embryologic origins of the kidney)
Early in the Week _ the intermediate mesoderm in the neck region of the embryo becomes the __________
4
pronephros
Pronephros are made up form what 2 parts?
Pronephros = pronephric duct + rudimentary pronephric tubules
Pronephric duct drains into ______
cloaca
Pronephros are the _____________
Rudimentary kidneys (lower fish e.g. lamprey)
Do the pronephros degenerate and if so when?
In humans, the pronephros mainly degenerates by Week 5 (except the pronephric duct)
What forms the Mesonephros and when?
Mesonephros = Intermediate mesoderm in trunk region, late Week 4
_________ duct now becomes the mesonephric duct
Pronephric
___________ ______ develop and drain into the mesonephric duct
Mesonephric tubules
Mesonephros functions as the ______ for approx. 4 weeks.
kidney
what comes after Mesonephros?
The metanephros or the definitive kidney
When do the metanephros start to forma nd when do they function
The metanephros starts to develop from about Week 5, but starts to function around Week 9
what does the developemnt of the metanephros consist of?
- A ureteric bud that develops off the mesonephric duct
- Metanephric mesoderm (the most caudal part of the intermediate mesoderm)
what happens to the mesonephos?
Much of the mesonephros will be incorporated into the developing gonad
(Undifferentiated cells from the yolk sac migrate in to form the spermatogonia/oogonia)
The mesonephric tubules become the rete testis
The mesonephric duct becomes the vas deferens (tiny muscular tube in the male reproductive system that carries sperm from the epididymis to the ejaculatory duct)
(In females the mesnephros becomes the ovary but the tubules and mesonephric duct degenerate)
Metanephros – Ureteric bud – describe its further development
The ureteric bud undergoes repeated branching at its distal end
The stalk becomes the ureter, the expanded cranial end becomes the renal pelvis
The first 4 generations of branches become confluent to become the major calyces
The next 4 generations form the minor calyces
The remaining generations form the collecting tubules
describe the developemnt of the nephron
The ureteric bud and the metanephric mesoderm reciprocally induce each other
Green = ureteric bud
Brown formed form metanephric mesoderm
Same of different?
Nephron vs Uriniferous tubule
Nephron = Renal corpuscle + PCT + Loop of Henle + DCT
Uriniferous tubule = Nephron + Collecting duct
Nephron develops from _________ _________
Collecting duct and calyces, pelvis, ureter develop from the _________ ___
Nephron develops from metanephric mesoderm
Collecting duct and calyces, pelvis, ureter develop from the ureteric bud
describe the ascent of the kidneys
Kidneys initially lie on either side of the bladder and in the developing pelvis.
Appears to “ascend” into the abdomen mainly due to differential growth of lower body inferiorly away from kidneys
Kidneys come to lie in upper abdomen (T12-L3)
Hilum rotates from ventral to medial (~90degrees)
Ascent stops when they come in contact with adrenal glands
Segmental breakdown and reform of vascular supply during ascent
Anomalies in development
in summary:
- ______ and _____ = urinary bladder and urethra
- Intermediate mesoderm develops into the rudimentary __________ in neck (week 4), __________ in trunk region (week 5 to 9) with a duct and tubules. ____ drains into cloaca
in summary:
- Allantois and cloaca = urinary bladder and urethra
- Intermediate mesoderm develops into the rudimentary pronephros in neck (week 4), Mesonephros in trunk region (week 5 to 9) with a duct and tubules. Duct drains into cloaca
in summary:
- Ureteric bud grows out of the caudal end of the ___________ duct…
- …and branches to form the renal pelvis, calyces and ________ duct
- The ______ bud and the __________ mesoderm reciprocally induce each other
in summary:
- Ureteric bud grows out of the caudal end of the mesonephric duct…
- …and branches to form the renal pelvis, calyces and collecting duct
- The ureteric bud and the metanephric mesoderm reciprocally induce each other
in summary:
- The kidneys “rise” due to differential growth of ____________ structures and acquires ___ blood vessels
- Rotates so that the hilum faces ________
in summary:
- The kidneys “rise” due to differential growth of abdominopelvic structures and acquires new blood vessels
- Rotates so that the hilum faces medially
