Renal Embryology Flashcards
Intermediate Mesoderm characteristics ( location, systems)
- location: trunk, lateral to each somite
- segments into cylindrical structures
- produces urinary and genital system
- urinary system develops first
Urogenital System ( urogenital ridge)
Urogenital ridge
- longitudinal band of mesoderm forms on each side of dorsal aorta
Developmental pathway of Urogenital System
urogenital ridge-> nephrogenic cord-> pronephros-> mesonephros-> metanephros
Pronephros ( characteristics, age, location, importance)
- rudimentary
- bilateral
- transitory
- shows up in 4th week,
- in cervical region
- ducts run caudally & open into cloaca
- degenerate 24-25 days
- persist and used by mesonephros
importance
- initiate cascade leading to formation of definitive kidneys
Mesonephros ( characteristics, age, location, components, fate) (lots of details)
- functions briefly during early fetal period
- bilateral
- transient
- shows up late 4th week-> 12th week
- caudal to pronephros
- Mesonephric ducts & mesonephric tubules
- ducts develops 1st
- induce tubules from surrounding intermediate mesoderm
Mesonephric Tubules-> renal corpuscle
1) Medial End of tubule= glomerular capsule ( cup shaped)
2) wraps around glomerulus (know of capillaries)
function as interim kidney from 6th-10th week -> produce small amount of urine
10th week- stop function
- will regress in females
- will form efferent ductules in males
Metanephros ( components ( 2), location, age)
- permanent kidneys
- 5th week
- caudal end of each mesonephric duct induces the ureteric bud
1) ureteric bud= outgrowth of mesonephric duct
2) metanephric blastema= from nephrogenic cord
Functional and definitive kidney by 9-10th week
-has excretory and collecting portions
Ureteric bud and Collecting System ( form and fate, generation)
- Ureteric bud elongate and penetrate blastema-> form renal pelvis
- stalk of uretic bud becomes the ureter
Cranial part of bud branches-> collecting tubules
- 1st generation of tubules enlarge-> major calices
- 2nd generations-> minor calices
Nephron Development ( 5 steps)
1) arched collecting tubule induces metanephrogenic blastema to form metanephric vesicle
2) Vesicle elongate to form metanephric tubules
3) Proximal end form glomerular capsule, invaded by glomeruli
4) Distal end: lengthen and differentiates-> PCT, DCT, Nephron loop
5) Each DCT contacts and arched collecting tubule-> mot connected
blastema-> vesicle-> tubules-> GC, PCT,DCT, nephron loop
Vasculature & Ascent of Kidneys
(location of kidney, age, branches (first branch, former branch) , blood supply) DETAILED
- Permanent kidneys
- within pelvis
- ascend into abdomen
Hilum- medially rotate 90 degrees
9th week- adult position, in contact with suprarenal glands
-blood supply from vessels that are closest
First branch: from common iliacs
definitive renal arteries: from abdominal aorta
Former branches- involution and disapper
Embryonic Kidney (2) vs. Adult Kidney (4)
Embryonic Structures
1) Ureteric Bud (collecting portion)
2) Metanephric blastema (excretory portion)
Adult Structures
1) #1 becomes ureter, renal pelvis, major & minor calyces, collecting ducts
2) #2 becomes bowman’s capsule, PCT, LOH, DCT
Unilateral Renal Agenesis
- form 1 functional kidney
- more frequent in males
- typically asymptomatic
- suspected in infants with 1 umbilical artery
Bilateral Renal Agenesis
- Oligohydramnios
- decrease volume of fluid
- Nonviable
- pulmonary hypoplasia
- associated with Potter Syndrome (20%)
Duplication (cogenital anomalies of kidney/ureter)
- abnormal division of ureteric bud
incomplete division= divided kidney & bifid ureter
complete division= double kidney & bifid ureter or separate ureter
Horseshoe Kidney
- fusion of inferior poles
- asymptomatic
- ascent prevented by IMA
Accessory Renal Vessels
- Many renal arteries (2-4)
- 25%
- can obstruct ureter-> hydronephrosis
End arteries- if damaged/ligated-> ischemia
Polycystic Kidney Disease (embryo)
- autosomal recessive
- mutation in PKHD1
- Cysts in both kidneys
- renal insufficiency
- 1/4 pulmonary hypoplasia
Multicystic dysplastic kidney disease
- abnormal development of renal system
- cysts: dilation of LOH
- mostly: one kidney affected
Urogenital Sinus (what is it part of, what is separated by, parts, function, embryological development) DETAILED
- Ventral cloaca (distal hindgut) = urogenital sinus and anorectal canal
- separated by urorectal septum
- important for bladder & urethral development
3 parts
1) vesical part= most of urinary bladder
2) pelvic part= forms neck of bladder, prostatic urethra (m) or urethra(f)
3) phallic part= form spongy urethra(m) or lining of vaginal vestibule ( f)
Week 4-6:
- mesonephric duct incorporated into posterior wall of bladder -> ureteric bud attaches to connect it to bladder wall
- openings of mesonephric duct are carried inferiorly to pelvic urethra-> form TRIGONE ( triangular region of mesonephric& & ureteric ducts blend into posterior bladder )
Bladder Development (develop from where, layer, continuous with )
- from vesical part of urogenital sinus
- Epithelium- derived from endoderm (urogenital sinus)
- Submucosa & muscularis= derived from splanchnic mesoderm
- Trigone= derived from intermediate mesoderm (mesonephric ducts)
Bladder is continuous with allantois
- Fetal membrane development from hindgut
- Allantois constricts & forms the urachus -> apex of bladder-> umblicus -> median umbilical ligament
Exstrophy of bladder
- aka extopic vesicae
- mostly males
- arises during body folding (4th week)
- defective closure of ventral abdominal wall
- exposure of mucosa of posterior wall of bladder
Epispadias
- males
- Urethral opening is on dorsum of genital tubercle rather than on its ventral side
Urachal Anomolies (3)
1) Urachal cysts: remnants of epithelia lining of urachus that can become infected & enlarged
2) Urachal sinus: end of urachus remains open into bladder (inferior region) or umbilicus ( superior region)
3) Urachal fistula ( most severe): entire urachus remains patent & allows urine to escape from umbilical orifice
Suprarenal Gland characteristics (4)
- Epi, NE, Aldosterone, cortisol
- above each kidney
- gland has outer cortex & inner medulla
- gland surrounded by CT capsule
Suprarenal Gland: CORTEX (zones)
1) Zona Glomerulosa: produce mineralocorticoids (regulate electrolytes)
- bundles of yarn
2) Zona fasciculata: produce glucocorticoids ( regular blood glucose levels, lipid metabolism)
- cords/fascicles/ bundles
3) Zona reticularis: produce sex hormones, estrogen& testosterone ( protein synthesis in sex cells)
- little network/meshwork
Suprarenal Gland: MEDULLA
- form inner core of the gland
- chromaffin cells (specialized postganglionic sympathetic neurons-NCC derived)
- EPI/ NE
Development of Suprarenal Gland
1) 5th week- coelemic epithelium delaminates and enters surrounding mesoderm-> fetal cortical cells
2) NCC migrate to medulla-> differentiate into chromaffin cells post-ganglion sympathetic neuron( Epi/Ne)
3) Fetal cortex regresses (2nd month PN)
- definitive cortical cells reorganize: zona glomerulosa, zona fasciculata, zona reticularis
4) Fetal cortex will secrete dehydroepiandrosterone (DHEA), ACTH, glucocorticoid
- converted by estradiol
- essential for pregnancy maintenance
Capsule derived from …
Cortex derived from …
Medulla derived from…
- mesonephric mesoderm
- coelomic epithelium (somatic mesoderm)
- NCC
