Urinary

Question 0

Describe the positional changes of the kidneys and understand now congenital anomalies of position and renal vessels occur

Answer 0

Kidneys ascend (pelvis –> abdomen) due to migration and expansion of caudal region
Migration includes cranio-caudal shift (L4-L1/T12), lateral displacement (meet adrenals), 90 degree rotation (pelvis faces midline)
Form new blood supply that regresses during ascension
Accessory arteries
Horseshoe kidney (fused isthmus)
Pelvic kidney

Question 1

Describe the three sets of excretory organs - pronephron, mesonephros and its duct, metanephros, the permanent kidney

Answer 1

Pronephron (wk4) - cervical, never functions in humans, pronephric duct (cervical –> cloaca)
Mesonephros (wk4-8) - tubules develop caudally, mesonephros duct + tubules = embryonic kidney, no preservation of water
Ureteric bud - development of collecting system, excretory compartment
Metanephros (wk8) - true kidney

Question 2

Describe the formation of the urinary bladder and urethra

Answer 2

Bladder (hindgut) is derived from caudal part of primitive gut tube
Allantois (superoventral diverticulum of hindgut) extends into umbilical cord
Allantois –> urachus (median umbilical ligament)
Urerectal septum –> urogenital sinus and anorectal canal
Narrowing of lower urogenital sinus = urethra

Question 3

Explain the embrological basis for common congenital disorders of the urinary tract e.g. horseshoe kidney, ectopic urethral orifices, ex trophy of the bladder and urachal anomalies

Answer 3

Horseshoe kidney - fused isthmus, kidneys touch due to rotation during ascension
Ectopic urethral orifices - splitting of ureteric bud (incontinence), hypospadias (urethra opens on ventral side of penis)
Extrophy of the bladder - protrusion of bladder through abdominal wall
Urachal fistulae e.g. rectum, belly button