urogenital one Flashcards
what is origin of urogenital system?
the intermediate mesoderm
what part of primordia becomes male?
mesonephric
what part of primordia becomes female?
paramesonephric
what does intermediate mesoderm form on either side of the aorta?
urogenital ridge
where is intermediate mesoderm?
between somites and lateral plate mesoderm
how does urogenital ridge form?
with lateral folding of embryo, intermediate mesoderm bulges into the peritoneal cavity
what two structures are formed in urogenital ridge?
nephrogenic cord (kidney) and gonadal ridge (genital)
what three sequential kidneys does nephrogenic cord form from head to tail?
- pronephros
- mesonephros
- metanephros
what is mesonephric duct?
embryonic ureter
what is metanephric diverticulum?
basis of our kidney
role of pronephros
forekidney; rudimentary, nonfunctional, 4th week
role of mesonephros
midkidney -(second month) temporary, functional, amphibians, ducts are conserved as male genital ducts and become efferent ductules of testes
role of metanephros
hindkidney - permanent, developed at 5th week. will become permanent kidneys
permanent kidneys develop from two source:
metanephric diverticulum or ureteric bud
metanephric mass of intermediate mesoderm
ureteric bud
primordium of ureter, renal pelvis, calices, and collecting tubules in the pyramids (collecting system)
metanephric mass of intermediate mesoderm
will differentiate into kidney nephrons.
what becomes ureter
the stalk of utereric bud
what will distal portion of ureteric bud do?
undego repetitive branching
what is transcription factor WT1?
regulates synthesis of Glial-derivid neurotrophic factor (GDNF) which induces branching of ureteric bud
how long do ureteric buds develop?
continue to bifurcate until 32nd week, producing 1 to 3 million collecting ducts
until when are nephrons formed?
until birth. after birth they increase in size, not in number
how does differentiation of nephrons start
with metanephric tissue cap, which differentiatews into metanephric vesicles, which form s-shaped metanephric tubules. proximal end of tubules is invaginated by small blood vessels. capillaries differentiate into glomerulus. metanephric vesicles and tubules become bownman’s capsule, proximal convoluted tubule, loop of Henle, distal convoluted tubule.
kidney ascent
mesonephros degenerates as kidney ascends. due to embryo growth.
what hooks up to kidneys as they ascend?
sequential arteries. some may persist. kidney becomes retroperineal.
when do metanephric kidney and glomerular filtration begin to work?
at approx week 9.
are fetal kidneys responsible for waste excretion?
no. placenta does this.
urorectal septum
divides cloaca into rectum and urogenital sinus with bladder, pelvic and phallic parts
origing of bladder and urethra
endodermal cloaca
how is cloaca partitioned?
dorsal portion: rectum and anal canal
ventral portion: bladder and urogenital sinus
what does urogenital sinus give rise to?
bladder and lower urogenital tracts
indifferent stage of sexual development
early genital development. gonads do not begin to attain sexual characteristics until week 7. external genitalia do not acquire distinct masculine or femininte char. until week 12
primordial germ cells visible when and where
4 weeks in yolk sac
primordial germ cells migrate into
along dorsal mesentery into gonadal ridges. if they do not migrate, gonads do NOT develop.
indifferent gonads
indentical in both sexes before week seven. development begins with gonadal ridge. then will consist of cortex and medulla.
germ cells migrate along dorsal mesentery and
by week six, induce differentiation of the gonad into testis or ovary
paramesonephric ducts
form during week six lateral to mesonephric ducts
what are primary sex cords?
fingerlike projections of epithelial cells that grow into mesenchyme of the gonadal ridge and form cortex and medulla
what does cortex develop into?
ovary in embryos with XX chromosomes. medulla declines.
what does medulla develop into?
testes in embryos with XY chromosomes. cortex regresses.
testis development steps
a. paramesonephric duct degenerates
b. primary sex cords become seminiferous cords, filled with sertoli cells.
c. mesonephric duct becomes ductus deferens
ovary development steps
a. mesonephric ducts degenerate
b. secondary sex cords - cortical cords break up inhto primordial follicles
c. no tunica albuginea
two paramesonephric ducts fuse in midline to form uterus
what tissue is involved in external genital development?
mesoderm and ectoderm around cloacal membrane
primordial tissues of external genitalia from from
- a pair of labrioscrotal folds
- a pair of genital folds
- an anterior genital tubercle
genital tubercle
forms a primordial phallus
genital folds
inner and outer extend dorsally from genital tubercle.
urogenital folds
inner folds
labioscrotal folds
develop on each side of urogenital folds. grow toward each other and fuse to form scrotum.
differentiation of female genitalia
genital tubecle elongates and eventually becomes clitoris
urogenital folds form labia minora
labioscrotal folds become labial majora
prepuce
foreskin
origin of penile urethra
ventral fusion of the urogenital sinus
original of navicular fossa in glas
ectodermal invagination from end of penis
how does mesonephros change function?
from urinary to genital in the male
what can improper interaction of epithelium and mesoderm lead to in the development of the metanephric kidney?
lack of glomerular development
cause of ectopic kidneys
result of an incomplete or missing ascent (kidney is stuck in pelvis)
what is hydronephrosis?
(enlarged renal pelvis) swelling of one kidney due to a backup of urine by the compressed ureter. artery blocks ureter. urine passage from kidney is blocked by renal artery. renal veins can also cause it. surgical treatment.
crossed kidney/ crossed ectopia
kidney migrates to the other side so that both kidneys are on same side
horseshoe kidney
two kidneys become fused in ascent. in more than 90% of cases, fusion occurs along lower pole. normally asumptomatic.
duplex kidney
the development of an extra kidney or partially fused kidney on one side or the other. a kidney can also have two ureters.
POLYCYSTIC KIDNEY DISEASE
ARPKD, autosomal recessive disease.
multiple fluid filled cysts form in kidneys. 1:2000 births. lethal if not treat by transplantation.
thought to be caused by abnormal cell proliferation in the tubule cells that leads to blockage of the tubules resulting in fluid build-up in segments of the tubules.
how is PKD treated?
control high blood pressure
surgery to reduce pain
antibiotics to resolve infections
female pseudohermaphroditism
(male external genitalia in female)
intersexual condition: chromosomally and gonadally female with XX karyotype
1:10,000 births
cause: mother exposed to excessive androgens
congenital adrenal hyperplasia
usually no ovarian abnorality, but excessive production of testosterone
masculinizing materla tumors also cause this
congeintal adrenal hyperplasia
autosomal recessive, decreased synthesis of cortisol due to an enzyme deficiency
male pseudohermaphroditism
intersexual condition. XY, 1:10,000
ext. and int. genitalia are variable caused by variations in devt of external genitalia and paramesonephric ducts
caused by inadequate production of testosterone or reduced tissue responsiveness in the fetus
this can be caused by genetic defects in enzymatic production of testosterone by fetal testes and interstitial cells of testes
androgen insensitivity syndrome (AIS)
1:20,000 normal appearing female but XY masculinization of male genitalia in fetus is impaired external ge. are female uterus doesnt work amenorrhea testes in abdomen
results from fact that target male reproductive cells are resistant to testosterone (androgen receptor problem)
