34. Development of the Kidney and Adrenal Gland Flashcards
In the early, embryo, what are the 4 common, major structures (embryonic ducts)?
What ducts degenerate in females and males?
Paramesonephric (Mullerian), mesonephric (Wolffian), immature gonad (eventually forms testes/oviducts), mesenchyme
Female: mesonephric duct degenerates, apart from lower portion which forms ureteric bud. Paramesonephric duct forms oviduct
Male: mesonephric duct forms male reproductive tract, lower portion forms ureteric bud. Paramesonephric duct degenerates.
What are the 3 embryonic kidneys? What are their fates?
What 2 embryonic structures is the metanephric kidney formed from? Describe the process.
Pronephric and mesonephric (form quickly and degenerate) and metanephric (circled in pic 1). All were formed from mesonephric duct.
1) Ureteric bud derived from mesonephric duct (green in pic 2)
2) Metanephric bud (blastema) derived from mesenchyme (red in pic 2)
Ureteric bud grows out of mesonephric duct and comes into contact with mesenchyme running down embryo sides -> communicates and initiates kidney development (starts to bifurcate and from the 2 calyces)
List the structures that the following give rise to:
a) Ureteric bud
b) Metanephric bud
Describe how the excretory compoents of the kidney form.
a) ureter, renal pelvis, major and minor calyces, collecting tubules. Lots of bifurcation (1-3mill CTs). Collecting system of kidney
b) renal glomerulus + capillaries, Bowman’s capsule, PCT, LoH, DCT. Excretory components of kidney
Each collecting tubule forms in metanephric blastula, has bit of mesenchyme on end of it, and when it comes into contact with CT => divide, elongate and hollow out until forms long excretory component (pic)
Describe the ascent of the kidney.
What is it called when the kidney fails to ascend?
What is kidney agenesis?
Metanephros located in sacral region (S1). Ascends as tail of embryo unfolds. Final location upper lumbar region (T12). Transitory renal arteries degenerate and new renal arteries form.
Ectopic kidney. Prob totally functional.
Failure of kidney to form. Unilateral or bilateral. Often associated with defects in uteric bud formation e.g. UB doesn’t form OR UB doesn’t come into contact with metanephric mesenchyme OR renal arteries fail to form with embryo development
Describe bilateral renal agenesis.
What is a bifid ureter? What are the 2 types?
Rare, baby doesn’t survive after birth. In utero, foetal kidney imp for generation of amniotic fluid. BRA = reduction in amniotic fluid (oligohydramnios) = birth defects incl. failure of lung dev and club foot.
Ureter splits in 2. Types:
1) Duplicate (supernumerary) kidneys: ureteric duct split into 2 and each piece has piece of mesenchye around it -> 2 kidneys form (split after contacts mesenchyme)
2) Duplicate ureter: get v large kidney with 2 ureteric ductal systems (split before contacts mesenchyme)
All functional - pt unaware
Describe 2 types of ectopic kidney.
What is a polycystic kidney? What are the 2 types?
1) Pelvic kidney: remains in pelvic region (usually 1). Can have both poles of kidneys fuse - pancake kidney. One still works.
2) Horseshoe kidney: kidneys fuse in pelvic region (1 pole), form single U-shaped kidney, can’t ascend due to inferior mesenteric artery
Kidney develop fluid-filled cysts, 50% kidney failure by 60yo. Will need transplant/dialysis. Types:
1) Autosomal dominant (more common, polycystin mutation)
2) Autosomal recessive (fibrocystin mutation)
85-90% of autosomal dominant polycystic kidney disease is associated with mutations in polycystin (PKD-1). What is a ciliopathy and how is it related?
Describe the mechanism of cyst growth.
Defects in primary cilia (polycystins are localised to primary cilia). Primary cilia are involved in cell adhesion, Ca2+ transport and cell cycle)
Cysts originate as dilations of intact tubule walls, enlage and lose contact with nephron. Cyst epithelium becomes secretory - increased fluid secretion into cyst lumen. Increased proliferation of cyst epithelium.
Describe the regions and zones of the adrenal gland which sits atop kidney.
Where does each region originate from?
What do the following produce:
a) Cortex
B) Medulla
What is congenital adrenal hyperplasia?
2 regions: medulla (inner) and cortex (outer, divided into 3 zones: zona retucularis, zona facicularis, zona glomerulosa (outermost))
Medulla - neural crest. NC cells migrate to coelomic cavity wall
Cortex - mesenchyme. NC cells interact with mesenchymal cells from the coelomic wall. Epithelial cells zone out to from diff zones.
Cortex: produces steroid hormones: mineralocorticoids (e.g. aldosterone), glucocorticoids (e.g. cortisol), androgens (e.g. testosterone)
Medulla: catecholamies (NA and adrenaline)
Adrenal cortex fails to make cortisol due to defect in enzyme 21-hydroxylase
