Development and Congenital Abnormalities of the Urinary System

Question 1

What are the hereditary disorders of tubule function?

Answer 1

• Bartter’s syndrome (Type 1)
• Gitelman’s syndrome
• Liddle’s syndrome
• Pseudohypoaldosteronism
• Inactivating Mutations of Aquaporins

Question 2

Describe Bartter’s syndrome (Type 1)

Answer 2

• Impaired SLC12A2 transporter
• In loop of Henle
• Na+, K+, Cl- to make hypertonic area of medulla

Question 3

What are the effects of Bartter’s syndrome (Type 1)?

Answer 3

Loss of Na+ K+, much
H2O; hypercalciuria
-Same as loop diuretics

Question 4

Describe Gitelman’s syndrome

Answer 4

• Impaired SLC12A3

- Sodium and chloride uptake channel of distal tubule

Question 5

What are the effects of Gitelman’s syndrome?

Answer 5

Loss of Na+, K+, modest H2O

-Like thiazide diuretics

Question 6

Describe Liddle’s syndrome

Answer 6

-Hyperactive ASC (=ENaC)

Question 7

What are the effects of Liddle’s syndrome?

Answer 7

Volume expansion

(body) , hypertension
- Opposite of diuretics
- Can still treat with amiloride

Question 8

Describe Pseudohypoaldosteronism

Answer 8

• Inactive ASC (=ENaC)

- Aldosterone usually transcribes ASC

Question 9

What are the effects of Pseudohypoaldosteronism?

Answer 9

Na+ loss, K+ retention, high aldosterone (trying to correct problem)
-Like amiloride

Question 10

What are the effects of Inactivating Mutations of Aquaporins?

Answer 10

(In collecting duct)
Nephrogenic Diabetes insipidus
(polyuria, polydipsia)
=more urine flow
Insipidus= dilute

Question 11

What are the problems outside the kidney?

Answer 11

• Addison’s disease

- Psychogenic polydipsia

Question 12

Describe Addison’s disease

Answer 12

-Destruction of adrenal glands
=Loss of Na+, hyperK+, hypovolaemia
=Less aldosterone- spironolactone

Question 13

Describe Psychogenic polydipsia

Answer 13

-Continuous thirst

=Whole body hypoosmolarity (diluting)

Question 14

Describe simple embryonic kidneys (pronephros)

Answer 14

-Leaky capillaries
-Ciliated funnel that drags fluid from capillaries
-Proximal tubule
-Drains into long pipe (nephric Wolffian duct) into cloaca (common exit with gut)
=No true glomerulus

Question 15

Describe the mesonephros

Answer 15

• Second kidney formed
• Both attached to nephric duct
• More advanced nephrons
• Leaky capillaries and ciliated funnel budded off
• More convoluted tubules
• Develop next to gonads
• Males= some tubules co-opted by testis

Question 16

What do the parts of the mesonephros (temporary kidney) become in the adult male testis?

Answer 16

• Tubules= epididymis

- Nephric duct= vas deferens

Question 17

Describe the metanephros

Answer 17

-What will become our kidneys
-Specialised mesenchyme
-Branch from cloaca that grows into metanephrogenic mesenchyme= urine collecting duct system
=Induces cells of mesenchyme to make stem cell populations that will both maintain themselves and make epithelia that make nephrons
(this is why the nephron stops at DCT)

Question 18

Describe the development of the bladder

Answer 18

• Starts to form from where the nephric duct and the ureter bud diverge as they come into the cloaca
• Part of allantois
• Nephric duct and ureter flow into bladder, separate at junction

Question 19

Describe the development of the prostate

Answer 19

• Prostate glands at junction

- Below bladder

Question 20

What are the components of semen and what glands make them?

Answer 20

-Testis – sperm
• Prostate – citric acid (energy and buffering), enzymes, acidic
proteins
• Seminal Vesicle – fructose (energy), basic proteins (various modulators of immune response)

Question 21

Describe the timing of release during ejaculation

Answer 21

• Prostate
• Epididymis
• Seminal vesicles

Question 22

Describe male development of nephric and Mullerian ducts

Answer 22

• Indifferent gonad develops testis cords
• Testis cords connect to some mesonephric tubules (->epididymis)
• Mullerian duct regresses
• Distal nephric duct sprouts seminal vesicles – the part of the nephric duct distal to this is the ejaculatory duct
• Urethra sprouts prostate and bulbourethral glands.

Question 23

Describe female development of nephric and Mullerian ducts

Answer 23

• Indifferent gonad develops into an ovary
• Upper Mullerian ducts
become fallopian tubes
• Mullerian ducts converge & fuse to become the uterovaginal canal
• Nephric ducts and mesonephros degenerates
• Uterovaginal canal forms uterus and upper part of vagina. (Lower part from urogenital sinus, part of cloaca)

Question 24

Describe the development of the external genitalia

Answer 24

-In undifferentiated stage
=phallus ending in gland, urogenital folds and urogenital groove between
-In females: folds= labio-scrotal swellings= labia, phallus= clitoris
-In males= more growth of phallus to become penis, labio-scrotal swellings fuse along midline forming scar called a raphe, urethra moves from original opening site to end of penis

Question 25

Contrast the male and female urethras

Answer 25

• Male: urethra runs along penis and opens at end

- Female: urethra ends within vulva and does not run to end of clitoris

Question 26

What is Renal Agenesis?

Answer 26

• Bilateral – No kidneys form. Rare; fatal after birth.
Lack of amniotic fluid causes Potter’s Facies.
• Unilateral – One kidney missing. Common
(1/500). Often no clinical implications unless
some bright surgeon removes the working one.

Question 27

Describe what Potter’s Facies look like

Answer 27

-Flat nose
-Flat chin
-Ears against head
=Normally amniotic fluid provides bubble-like cushion (most foetal urine)

Question 28

Describe polycystic kidney disease

Answer 28

-Most common genetic disease
=Very large
=Cysts grow and destroy normal kidney underneath
=Variability in onset and mechanism

Question 29

Describe a supernumerary ureter

Answer 29

• Nephric duct gives rise to two branches
• Usually no problem if unite and go into bladder properly
• Or can join beneath the bladder so is not stored- constant urine flow in urethra, more risk of infections tracking into kidney as no bladder

Question 30

Describe Pelvic Kidney

Answer 30

• Misplaced kidney, remains in pelvic region
• Male= little consequence
• Problem with pregnant females
• If both kidneys in pelvis= fuse and jammed by blood vessels (horseshoe)

Question 31

What are the congenital abnormalities of the cloaca (common exit in embryo)?

Answer 31

Failure of correct positioning of Rathke and Tourneaux (fold of tissue)
folds results in;
• Rectovaginal fistula (infection risk)
• Rectoprostatic fistula
• Rectoclocal canal (rectum, vagina and urethra unite
inside body).
-In males, incomplete migration of the urethral groove from the base of the penis to its tip results in hypospadias