Embryology Flashcards
What tissue is the urinary system derived from?
Intermediate mesoderm.
What is the pronephros?
Is the developing kidney/urinary system that occurs in the lower cervical region of the embryo, where the intermediate mesoderm segments.
What is the mesonephric duct?
A condensation of cells that form into a tube-like structure behind the intermediate mesoderm that is forming the pronephros.
This tube-like structure grows down to make connections with the back of the cloaca.
Pronephros and mesonephric duct will make connections together during development.
How many mesonephric tubules are formed?
40 pairs produced craniocaudally but they regress by the end of week 5 to leave about 20 pairs remaining in the upper lumbar region (L1-L3).
They then differentiate into excretory units and function between weeks 6-10 before they then regress.
Some of these structures will remain in males to contribute to the male genital duct system but they will all regress in females.
What is the metanephros?
It appears at ~week 5.
Begins to function between weeks 9-11 when the mesonephric kidney gives up function to the kidney proper.
The metanephros forms the ureteric bud and metanephric blastema (which is what becomes the kidney proper).
When do the ureteric buds sprout from the distal mesonephric ducts?
Day 28.
When do the ureteric buds penetrate the metanephric blastema?
Day 32.
What is kidney agenesis?
Occurs if the ureteric bud is too short or doesn’t develop.
Which structure is the collecting system of the adult derived from?
The ureteric bud.
What adult structures develop from the ureteric bud?
Ureter.
Renal pelvis.
Major calyces.
Minor calyces.
Collecting ducts.
The collecting system.
What happenings in the branching of the ureteric bud to form the collecting system of the adult?
4 generations of branching in which each one bifurcates to give 2 more branches.
Then intussusception occurs where some of the branches being to merge back into one another to form the major calyces.
This happens again to give the minor calyces.
What adult structure is derived from the metanephric blastema?
Nephron.
What is a nephron?
The functional unit for the filtration of blood and the production of urine.
What are the 4 parts of the nephron?
Bowman’s capsule.
Proximal convoluted tubule.
Loop of Henle.
Distal convoluted tubule.
What vertebral level do the kidneys ascend to during weeks 6-9?
L1.
What are the developmental bladder defects that can occur?
Urachal fistula - if allantois is retained and does not regress.
Urachal cyst - cyst forming along the ligamentous structure of the regressed allantois.
Urachal sinus.
