Embryology of the kidneys, ureters and bladder Flashcards
what germ layers are the structures of the renal system derived from?
mesoderm
endoderm
shared embryological origin with reproductive system
what are the layers of the mesoderm?
paraxial mesoderm
intermediate mesoderm
lateral plate mesoderm
what are the parts of the lateral plate mesoderm?
somatic and splanchnic mesoderm
somatic mesoderm
contributes to abdominal body and cavity and cavity walls
lines each inner surface
splanchnic mesoderm
forms structures of abdominal viscera
lines outer surface
where does the uterine tube come from?
mesoderm
where does the uterus and uterine canal come from?
mesoderm
where does the vagina come from?
mesoderm and endoderm
where does the urethra come from?
endoderm
where does the external genitalia come from?
endoderm
what makes up the renal collecting ductal system?
ureters renal pelvis major calyces minor calyces collecting tubules
what makes up the renal excretory ductal system?
nephron
- renal corpuscle - glomerulus and bowman’s capsule
proximal and distal convoluted tubule
loop of henle
where do the renal tubules and ureters come from?
mesonephric system from mesoderm
where does the bladder and urethra come from?
cloaca of endoderm
what is the cloaca?
part of the distal portion of the embryonic hindgut
what does the mesonephric system give rise to?
renal tubules ureter reproductive ductal system uterine canal vagina
what does the cloaca give rise to?
urinary bladder
urethra
vagina
external genitalia
Haeckel’s biogenetic law
ontogeny recapitulates phylogeny
our developmental processes tend to remember and repeat our evolutionary history
seen in the development of urinary system
origin of development of urinary system
pronephros
what is pronephros
functional kidney in primitive fish
forms mesonephros
mesonephros
functional kidney in advanced fish
forms metanephros
metanephros
functional kidney in human
development of pronephros
from intermediate mesoderm
appears at beginning of 4th week, regresses by the end of 4th week
development of mesonephros
derived from intermediate mesoderm
gives rise to mesonephric ducts
what do mesonephric ducts form?
forms primitive excretory tubules and the primitive bowman’s capsule and primitive renal corpuscle that drain into mesonephric ducts
gives rise to ureteric buds
urogenital ridge
formed by mesonephros and gonads
metanephros
permanent kidney
5th week of development
gives rise to definitive excretory units
permanent kidney ductal system
collecting system development
ureteric bud penetrates metanephric tissue/ blastema
collecting tubules converge on minor calyces forming renal pyramids
what does the ureteric bud give rise to?
ureter
renal pelvis
major and minor calyces
generations of collecting tubules
development of excretory system
distal end of each collecting duct tubul covered by metanephric tissue cap
cells from this form renal vesicles form the s-shaped renal tubules - excretory tubules
formation of glomerulus - excretory system
at the other end of the renal tubule surrounding capillaries differentiate into glomerulus
which goes on to form the bowman’s capsule
formation of proximal and distal convoluted tubules
continuous lengthening of the excretory tubules
metanephros gives rise to?
excretory system of kidney
mesonephros gives rise to?
kidney collecting duct system
what are the embryonic sources of the definitive structures of the human kidney system?
ureteric bud from mesonephric duct of mesoderm
metanephric blastema of metanephric mesoderm
formation of nephrons
continues until birth
1 million per kidney
when does urine production start?
12th week of inter uterine life
what happens to urine in the uterus?
passed into amniotic cavity and mixes with amniotic fluid
the fluid is swallow by the fetus and recycled through the kidneys
responsibility of the kidneys in fetal life
not responsible for excretion of waste products, this is the role of placenta
kidneys at birth
have lobulated appearance which disappears during infancy due to further growth but no increase in number of nephrons
regulation of development of kidney system
epithelial mesenchymal interactions
genes
location of the kidney
originate in pelvic region but ascend to the posterior abdominal cavity
what causes the relocation of the kidney?
diminution of body curvature and growth of body in lumbar and sacral regions
changes in blood supply to kidney
in pelvic region = pelvic branch of abdo aorta
during ascent = arteries that branch from aorta higher up
lower vessels usually degenerate but may remain as accessory vessels
accessory renal arteries
common
derived from persistent embryonic vessels and enter one of the poles of the kidneys
renal tumour
wilms tumour
wilms tumour
cancer of kidney under 5 years old may occur in fetus genetic mutation associated with other abnormalities part of WAGR syndrome and Denys-Drash syndrome
syndromes affecting the kidney
WAGR syndrome
Denys-Drash syndrome
Denys-Drash syndrome
renal failure
ambiguous genitalia
Wilms tumour
malformation in renal system…
may also affect reproductive system
PKD
congenital polycystic kidney disease
numerous cysts form
oligohydramnios
reduced amniotic fluid
causes compression of uterine cavity
PKD inheritance
autosomal recessive or dominant or caused by other factors
ARPKD
rarer autosomal recessive PKD progressive disorder cysts form from collecting ducts kidneys become large and renal failure in infancy
ADPKD
more common
autosomal dominant PKD
cysts form from all segments of nephron
renal failure in adulthood - less progressive
pelvic kidney
kidney doesn’t ascend - remains in embryonic position
horseshoe kidney
kidneys may fuse at lower pole
ascent is arrested
development of bladder and urethra
formed from cloaca
endoderm
cloaca
at 4th-8th week
cloaca divides into urogenital sinus and anal canal by urorectal septum (mesodermal)
urogenital sinus
forms urinary bladder - continuous with allantois
urachus
formed from allantois
forms the median umbilical ligament
caudal portions of mesonephric ducts
absorbed into wall of urinary bladder so the ureters enter the urinary bladder separately
lining of bladder
originally mesodermal but becomes replaced by endodermal epithelium
epithelium of urethra
originates from endoderm in both sexes
epispadias
when urethral opening is on upper surface of penis
what is associated with exstrophy of the urinary bladder?
epispadias
exstrophy of urinary bladder
urinary bladder mucosa is exposed
