Development of the Urinary System Flashcards
intermediate mesoderm
nephrotome.
gives rise to the nephric structures of the embryo, portions of the suprarenal glands, gonads, and genital duct system
urogenital ridge
longitudinal elevation of mesoderm from transverse folding
divisions of urogenital ridge
nephrogenic cord–urinary system
gonadal ridge– genital system
three sets of nephric system that develop craniocaudally from nephrogenic cord
pronephroi–rudimentary and nonfunctional
mesonephroi– functions briefly during the early fetal period, excretory units and ducts
metanephroi–forms the permanent kidneys, most caudal
parts of the pronephric ducts used by next set of kidneys
mesonephric ducts, creates metonephric diverticulum (or uteric bud)
mesonephroi
excretory organs that appear late in 4th week, caudal to pronephroi. well developed, interim kidneys.
parts of the mesonphric kidneys
glomeruli and tubules
tubules open into bilateral mesonephric ducts (from pronephric ducts)
embryonic precursors to the efferent ductules of the testes
mesonphric tubules
functional adult derivatives of the mesonephric tubules
efferent ductules of testis
paradidymis
epoophoron
paroophoron
where do mesonphric ducts open into?
urogenital sinus (cloaca)
adult derivative of mesonephric ducts
appendix of epididymis/vesiculosa
duct of epididymis/epoophoron
ductus deferens/longitudinal duct; gartner duct
ureter, pelvis, calices, and collecting tubules of kidneys
ejaculatory duct and seminal gland
two parts of the metanephroi
excretory–metanephrogenic blastema (metanephric mass of mesenchyme), derived from caudal part of the nephrogenic cord
collecting–ureteric bud (metanephric diverticulum), from mesonephric duct near its entrance into cloaca
reciprocal induction
branching of the urteric bud– dependent on induction by the metanephric mesenchyme
differentiation of the nephrons depends on induction by the collecting tubules.
derivatives of nephronic cord and mesonephric duct as two functional parts of kidneys
nephronic cord–excretory, metanephrongenic blastema
mesonephric duct–collecting, uretic bud
collecting portion of kidney (ureteric bud)
ureter renal pelvis major and minor calyces collecting ducts collecting tubules
excretory portion (nephron) (metanephric blastema)
bowman’s capsule
proximal convoluted tubule
loop of henle
distal convoluted tubule
the second branching of ureteric bud and it’s stalk
stalk of ureteric bud= ureter
5-8=minor calices
second set of branching make minor calices coalesce via intussusception
development of the excretory portion of kidney
caudal part of the nephrogenic cord–>metanephrogenic blastema–>(meta)nephric vesicles elongate to (meta)nephric tubules which develop into the nephron (proximal/distal convoluted tubules, bowman’s capsule, loop of henle) due to invagination of proximal ends of glomeri
what constitutes a nephron
proximal and distal convoluted tubules, nephron loop (henle loop), glomerulus and capsule
when is the upper limit of glomeruli reached?
32nd week, nephron formation is complete at term. 2 million nephrons.
week nine, glomerular filtration begins
which convoluted tubule contains arched collecting tubule
distal convoluted
urine productivity
10-11th week begins
late pregnancy–500ml of urine added daily
700-1000ml by week 37
positional changes of kindeys
metanephric structures in pelvis, ventral to sacrum
ascent
medial rotation
retroperitoneal positioning
relocation of the kidneys to the abdomen and movement farther apart
disproportionate growth of the embryo’s body caudal to the kidney. this makes them contact suprarenal gland. normal adult position by 9th week.
during kidney ascension, they also
medially rotate 90 degrees, ventral location of hilum is changed to anteromedially
changes in blood supply to the kidneys
renal arteries (common illiac branches) from descending abdominal aorta distal end of aorta new branches from the aorta and the caudal branches of renal vessels disappear=permanent renal arteries
permanent renal arteries
branches from the abdominal aorta, right renal is longer and often more superior
renal agenesis
ureteric buds do not develop or the primordia (stalks of buds) of the ureters degenerate.
if the buds do not penetrate metanephrogenic blastema, the nephrons are not induced by collecting tubules to develop from metanephrogenic blastema.
clinical associations with renal agenesis
unilateral–males, left kidney. usually unnoticed. suspected with kids in single umbilical artery
bilateral–oligohydromnios, incompatible with life. pulmonary hypoplasia.
potter sequence–bilateral renal angenesis.
malrotated kidneys
hilum is anterior, fetal retains embryonic position.
hilum is posterior, too far rotation.
hilum is lateral, lateral rotation instead of medial.
associated with: ectopic kidneys
ectopic kidneys
malrotation
usually located in pelvis (some inferior abdomen)
internal or external iliac arteries or abdominal aorta remain blood supply.
pelvic kidneys– kidneys fail to ascend
pancake kidneys (discoid)
pelvic kidneys (failure to ascend) are too close together. remain in pelvic region
horseshoe kidney
inferior poles of two metanephroi fuse, crossing over ventral aorta
pubic region (anterior to inferior lumbar vertebra)
caught under inferior mesenteric artery during ascent
normal collecting systems, ureters in bladder– no symptoms
congenital polycystic kidney disease
autosomal recessive or dominant
ARKPD- at birth or in utero, both kidneys contain many small cysts, early life renal failure. death shortly after birth
ADKPD– more common, cysts in all regions of nephrons, less severe than recessive. associated with cysts in kidneys, ductal epithelia in the liver, pancreas, testis, and ovary
duplicated ureter
abnormal divisions of ureteric bud.
premature bifurcation before it enters the substance of the metanephric blastema
often, but not always asymptomatic.
predisposition to infections
ectopic ureter
does not enter urinary bladder (not incorporated into trigone), drains somewhere else
males-neck of bladder, prostatic part of urethra, ductus deferens, prostatic utricle, seminal gland
females-neck of bladder, urethra, vagina, or vestibule of vagina
common complaint of ectopic ureter
incontinence, urine flowing does not enter bladder. continual dribble. UTI
3 parts of urogenital sinus
vesical part
pelvic part
phallic part
vesical part of urogenital sinus
most of the bladder and continuous with allantois
pelvic part of urogenital sinus
urtethra in the neck of the bladder, prostatic part of the urethra in males, and entire urethra in females
phallic part
grows toward the genital tubercle (primordium of the penis or clitoris)
what develops from the vesical part of the urogenital sinus
bladder
trigone of the bladder
triangular area base of the bladder between the openings of the ureters, derived from the caudal ends of the mesonephric ducts
distal parts of mesonphric ducts
incorporated into dorsal wall of bladder as it englarges, contribute to the formation of the CT of the trigone.
movement of orifices of ureters due to traction exterted by kidneys as they extend
superolaterally and enter obliquely through base of bladder
males vs females, orifices of mesonephric ducts
males move closer together and enter prostatic part of urethras as the caudal parts develop into ejaculatory ducts
females- distal ends degenerate
epithelium of bladder is derived from
endoderm of the vesical part of the urogential sinus
other layers of bladder
adjacent splanchnic mesenchyme
urachus
thick fibrous cord that is a result of the allantois constricting. extends apex of the bladder to umbilicis. initially bladder is continuous with allantois.
the median umbilical ligament
the urinary system consists of
kidneys, ureters, urinary bladder, urethra
by weeks 8-12.
allantois and blood vessels
sausage-like diverticulum from caudal wall of umbilical vesicle extending into connecting stalk. these blood vessels become umbilical vessels
urachus
proximal part of the allantoic diverticulum, from bladder to umbilical region. become median umbilical ligament, from the apex of the urinary bladder to the umbilicus
urachal fistula
urine drains from its umbilical orifice and increases risk of UTI, proximal
umbilical urachal sinus
abcesses, proximal. urine leak through umbilical opening
vesicourachal diverticulum
increases risk for UTI,
urachal cyst
not usually detected except during postmortem, unless infected. life threatening if ruptures in peritoneal cavity
extrophy of bladder
males. exposure and protrusion of the muscosal surface of the posterior wall of the bladder. trigone of bladder and ureteric orifices are exposed. everted bladder.
epispadias (urethra opens on dorsum of penis), wide separation of pubic bones
** deficiency of anterior abdominal wall, incomplete median closure of the inferior part of the wall. abdominal wall and anterior wall of urinary bladder.
most of male urethra, entire female
derived from endoderm of the urogenital sinus
distal part of male urethra and epithelium of the terminal part of the urethra
in glans of penis, derived from solid cord of ectodermal cells, that grow inward from tip of glans.
terminal– surface ectoderm
connective tissue and smooth muscles around both urethra
splanchnic mesoderm
two areas of suprarenal glands
cortex–mesenchyme on each side of embryo between the root of dorsal mesentary and the developing gonad
medulla–adjacent sympathetic ganglion, neural crest cells
at birth, which part of suprarenal gland is larger
extensive cortex, produces steroid precursors that are used by placenta for estrogen synthesis
smaller medulla
rapidly becomes smaller as the fetal cortex regressed during first year of infancy
Congenital Adrenal Hyperplasia
autosomal recessive disorders that result in virilization of female fetuses.
genetic deficiency of suprarenal cortical enzymes (cortex)
increased release of adrenocorticotropin from anterior pituitary gland
increased release of adrenocoritcotropin
abnormal increase in cells of the suprarenal cortex and excessive androgen production
masculinization of external genitalia
Wilms Tumor
Mesodermal tumor, metanephric tissue has failed to differentiate into normal kidney tissue.
rapid growth, early metastasis. high survival rates
Asymptomatic abdominal mass
Malaise, anemia, weight loss
Occlusion of left renal vein
Hypospadias/Epispadias
hypospadia–urthral opening on ventral side of the penis
epispadia–urtethral opening on dorsal side of penis
