Flashcards in Session 2 - Embryology Deck (61)
What tissue in the tri-laminar disc does the kidney develop from?
• Intermediate mesoderm
What are the two areas post-gastrulation where there is no mesoderm between ecto and endoderm?
• The buccopharyngeal membrane (oral cavity)
• Cloacal membrane (anus)
How is the intermediate mesoderm organised?
• 3 systems develop sequentially
• Disappearance of one system marks the onset of development of the next
What is the first part of the renal system to develop?
• The pronephros
What is the second part of the renal system to develop?
• The mesonephros
What is the third part of the renal system to develop?
• The metanephros
What four structure make up a nephrotome?
• Bowman's capsule
• Proximal & distal convoluted tube
• Collecting duct
What is the pronephros?
• First kidney system in humans
What is the function of the pronephros?
• No direct function
• Provides pronephric duct which extends from the cervical region to the cloaca and drive the development of the mesonephros (becomes mesonephric duct)
What is the urogenital ridge?
• Region of intermediate mesoderm giving rise to both the embryonic kidney and the gonad
Is the mesonephros a functional kidney?
• Yes, but has no water conserving mechanism
• Has a very important role in the development of the male reproductive tract
What makes up the embryonic kidney?
• The mesonephros
• Made up of mesonephric tubules and the mesonephric ducts
In what direction do the mesonephric tubules develop?
Caudal to pronephric
Why is the mesonephros only thought of as a partial kidney?
• Can produce urine, but cannot concentrate it
How does the mesonephric duct drive the development of the definitive kidney?
• Sprouts the ureteric bud
Aside from driving the development of the definitive kidney, give a role of the mesonephric duct
• Drives development of male reproductive system
Where does the ureteric bud induce development of the definitive kidney?
• Within the intermediate mesoderm of the caudal region of the embryo
What is the collecting system of the kidney derived from?
• The ureteric bud
What is the excretory component of the kidney derived from?
• The metanephric tissue cap
• Intermediate mesoderm under the influence of the ureteric bud
What is the ureteric bud the primordium of?
• The ureter
• Renal pelvis
• Collecting tubules
What is the "ascent" of the kidney?
• The metanephric kidney first appears in the pelvic region
• Undergoes an apparent caudal to cranial shift, crossing the arterial fork formed by vessels returning blood from the fetus to the placenta
Do the kidneys truly ascend?
• No, body undergoes cranial to caudal shift around them
What happens to blood supply of the kidney during ascendion?
• Kidneys receive blood from those arteries closest to them
Why is variation in renal blood supply so common?
• Due to the kidneys constantly changing blood supply during development
• Additional renal arteries may be present, or superior or inferior pole vessels
When would hydronephrosis occur?
• As a result of an inferior pole artery obstructing the ureter
What happens if the ureteric bud fails to interact with intermediate mesoderm?
• Renal agenesis will occur
What is one sided renal agenesis called?
Give five ways other ways things go awry in kidney development?
• Migration goes wrong
• Wilm's tumour
• Duplication defects
• Ectopic ureter
• Cystic disease
Outline a migration defect of the kidney
• If kidney fails to cross the arterial fork, it will end up lower than it should
• If this happens to both kidneys, a horseshoe kidney may appear due to fusion