Development of the Urinary System Flashcards
Where do the kidney systems begin to appear?
Posterior abdo wall, behind the peritoneum
From the mesoderm how many kidney system develop?
Three
1) pronephros = pronephric duct extends from the cervical region to the cloaca and drives the development of the next developmental stage
2) mesonephros = Mesonephric duct has an important role in the development of the repro system in the male, sprouts ureteric bud which induces devel of kidney
3) metanephros = true kidney capable of normal kidney function
Outline the pronephros
Produces duct
Extends from cervical region to cloaca
Drives devel of mesonephros
What is the mesonephros?
Mesonephric tubules devel
Tubules + duct = embryonic kidney
No water conservation ability
Sprouts ureteric bud which induces devel of kidney
What is the urogenital ridge?
Region of intermediate mesoderm giving rise to both the embryonic kidney and the gonad
What is the importance of the ureteric bud?
Undiff intermediate mesoderm
Metanephric blastema is present but requires presence of ureteric bud to send it signals to devel into metanephros (true kidney)
What are the stages of the ureteric bud forming a kidney?
Bud sprouts and contacts metanephric blastema
Bud expands and branches
Formation of major/minor calyx and renal pelvis
Where does the metanephric kidney first appear?
Pelvic region
Undergoes an apparent caudal to cranial shift, crossing the arterial fork formed by vessels returning blood from the fetus to the placenta
Describe the ascent of the kidneys
Shift up through the abdo
Gains new blood supply as it climbs, old vessels degenerate
Final position in the lumbar region
List the sequence of kidney ducts in developmental order
Primary nephric duct
Mesonephric duct
Ureteric duct
What things can go wrong with kidney devel?
Uretic bud fails to interact with mesoderm
Migration goes awry = inferior poles touch and fuse, then hocked on midline branch of aorta
Duplication defects = caused by splitting of ureteric bud - 2 separate ureters, extra lobes
Ectopic ureter = ureter doesn’t enter where it should = error in formation of ureter bud, incontinence
What is the urogenital sinus?
Ventral part of the cloaca formed after the cloaca separates from the anal canal
Becomes the bladder and urethra
How does the cloaca divide?
Cloaca divided into 2 compartments by urorectal septum
Anterior = urogenital sinus
Posterior = rectum/anal canal
Why does the cloacal membrane rupture?
Contains no mesoderm which is needed for CVS devel
= degenerates
Describe the formation of the urinary bladder and urethra
Urogential sinus - majority diff to form urinary bladder, inferior part devel to urethra
