Embryology Flashcards
What embryological tissue type makes up the urinary system?
Intermediate plate mesoderm forms the urinary and reproductive systems (GU system)
Define the allantois
The allantois is an outpouching of endoderm at the hindgut that extends into the body stalk
Define the cloaca
- The cloaca is the single posterior opening for a bird’s digestive, urinary and reproductive tracts and is used to expel faeces and lay eggs.
- Also found in human embryos before relevant structures have developed
What do you call the outpouching of endoderm at the hindgut that extends into the body stalk?
Allantois
What type of tissue is the allantois?
Endoderm
What type of tissue is the cloaca?
Intermediate mesoderm
What does the urogenital sinus form in developed embryos?
The urogenital sinus later forms the urinary bladder proximally and its caudal end forms the urethra
What forms the urachus?
Allantois will eventually become clamped, but will form urachus post-embryonically
What does the allantois form post-embryonically?
Urachus
What is the first primitive set of kidneys called?
Pronephros
What does the pronephros duct drain into?
Cloaca
When during development is the pronephros present?
Between week 4-5
What is the second primitive set of kidneys called?
Mesonephros
When during development is the pronephros present?
Week 5-9
What is the third primitive set of kidneys called?
Metanephros
Describe the development and embryological origins of the gonads
Much of the mesonephros will then be incorporated into the developing gonad (as well as undifferentiated cells from the yolk sac which migrate in to form the spermatogonia/ oogonia)
What do the mesonephric tubules and duct become in males?
In males, the mesonephric tubules become the rete testis and the mesonephric duct becomes the vas deferens
What do the mesonephros and the mesonephric tubules become in females?
In females the mesnephros becomes the ovary but the tubules and mesonephric duct degenerate
What does the ureteric bud and its stalk become?
- The ureteric bud from the mesonephric duct undergoes repeated branching at its distal end.
- The stalk of this bud becomes the ureter and the expanded cranial end becomes the renal pelvis.
What makes up a nephron?
Nephron = Renal corpuscle + PCT + Loop of Henle + DCT
What makes up a uriniferous tubule?
Uriniferous tubule = Nephron + Collecting duct
What does the nephron develop from?
Nephron develops from metanephric mesoderm
What does the collecting duct and tubules, the renal pelvis and the ureters develop from?
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
At what vertebral levels are the adult kidneys found?
T12-L3
When do kidneys stop ascending?
When they reach the adrenal glands
What % of the population have an accessory renal artery?
25%
