Urogenital System Development Flashcards
what layer is the kidney derived from?
intermediate mesoderm
where does the kidney development begin? does it migrate? if so, where to?
starts in the pelvis, and ascends to the abdomen
what do both of the kidneys and the gonads arise from?
the urogenital ridge (Intermediate mesoderm)
Specifically, what does the kidney come from?
the nephrogenic cord/nephrotome– its the tissue in the center of the urogenital ridge
what is the pronephros? where is it located? what does it connect to?
transient epithelial cords in the cranial intermediate mesoderm that connect to a pronephric duct which extends towards the cloaca (disappears in humans)
What is the mesonephros derived from?
upper thoracic to upper lumbar intermediate mesoderm
what does the mesonephros consist of?
renal glomeruli and renal tubules which open into the cloaca
what does the ureteric bud arise from?
the mesonephric duct
What is considered the definitive kidney? how is it formed (from what)?
the metanephros; the ureteric bud arises from the mesonephric duct and grows into the sacral intermediate mesoderm (at the metanephric blastema) where it induces the definitive kidney
What happens to the mesonephric tubules/ducts once the metanephros is formed?
they stop producing fluid and end up being involved in the development of the genital system
what is the metanephric blastema? what does it form?
a zone of the sacral intermediate mesoderm that once the ureteric bud grows into it, induces development of renal structures; IT FORMS THE NEPHRONS
what does the ureteric bud become?
the ureter, renal pelvis, calyces, and collecting ducts (tubules) of the kidney
Describe the reciprocal induction of the ureteric bud and metanephric blastema
the ureteric bud induces the metanephric blastema to form from the sacral intermediate mesoderm, and the metanephric blastem induces the ureteric bud to branch (into the ureter, calyces etc.)
Describe the results of branching of the ureteric bud
the first few generations of branching forms the major calyces, the next form minor calyces, and the next form the collecting tubules of the kidney
What does each blastema cap form?
a vesicle that lengthens in a tubular manner; one end forms the bowman’s capsule and surrounds the glomerulus, the rest forms the proximal convoluted, loop of henle, and distal convoluted tubules
what is the function of the kidney (in utero)?
produce and excrete fluid BUT DOES NOT REMOVE WASTE! the waste produces are removed by the placenta! The main function is to PRODUCE AMNIONIC FLUID!!
what can renal agenesis or urethral obstruction lead to?
oligohyrdaminos
Intermediate mesoderm in the sacral region gives rise to ________.
metanephros
the ureteric bud is derived from __________.
mesonephric duct
list the derivatives of the metanephric blastema
nephrons
when do the permanent kidneys begin to function?
9-10 weeks
failure of the kidneys to develop bilaterally results in _________.
oligohydraminos, hypoplastic lungs
what causes the retroperitoneal ascent of the kidneys?
actual migration of the kidney and expansion of the caudal region of the embryo
what supplies the kidneys as they ascend?
common iliac arteries then the lower abdominal aorta and finally the renal arteries
What causes renal agenesis?
faulty inductive interaction between the uteric bud and the metanephric mesoderm
Is unilateral agenesis symptomatic?
NO
What does renal agenesis cause?
do not produce aminonic fluid therefore oligohydraminos
What is congenital polycystic kidney disease? what are the two forms?
= numerous fluid filled-cysts form in the kidneys
- autosomal dominant = slow progression
- recessive form = early renal failure in infancy/childhood
what are common faulty migrations of the kidney?
- Pelvic kidney
2. Horseshoe kidney
What is horseshoe kidney? what arrests kidney ascent?
when the kidneys are fused at their INFERIOR POLES; the inferior mesenteric artery arrests kidney ascent
Do abnormal renal arteries present any clinical symptoms?
NO
What causes duplication of a ureter? where does the second ureter insert?
due to slitting of the ureteric bud; one ureter enters ectopicaly into the vagina, vestibule, or urethra
Due to the migration of the kidneys, other arteries in the pelvis and abdomen supply them before normal renal arteries from the abdominal aorta supply them. This may result in variation of the supply to the kidney if some of these earlier arteries persist. You might then see renal arteries arising from __________.
- common iliacs
2. loweradbominal aorta
How does a horseshoe kidney develop and what crosses over it?
inferior poles fuse as kidneys ascend; inferior mesenteric artery crosses the middle of the fused kidney
what divides the cloaca? what does it divide it into?
divided by the urorectal septum into a dorsal ANORECTAL canal and ventral UROGENITAL sinus
what lines the cloaca?
endoderm
what is the cloacal membrane divided into? do they rupture?
anal and urogenital membranes
what is the bladder and uretha derived from?
the UG sinus (the cloaca gets subdivided into a UG sinus and anorectal anal)
what is the epithelial lining for the bladder and urethra derived from?
the endoderm of the urogenital sinus
what is the muscle/CT of the bladder and urethra derived from?
the mesoderm that surrounds the UG sinus
What are all of the parts of the UG sinus derived from?
endoderm
what are the three parts of the UG Sinus?
- Vesical part
- pelvic part
- phallic part
what does the vesical part of the UG sinus form?
epithelium of urinary bladder
what does the pelvic part of the UG sinus form? IN MALES
epithelium of prostatic and membranous urethra, bulbourethral glands, and the prostate
what does the pelvic part of the UG sinus form? IN FEMALES
entire urethra, greater vestibular glands, and the sinovaginal bulbs which form the lower part of vagina and the hymen
what does the phallic part of the UG sinus form?
in MALES: lining of spongy urethra EXCEPT navicular fossa
in FEMALES: vestibule
what is the navicular fossa derived from?
ectoderm
why do the ureters and mesonephric ducts enter separately?
because the caudal parts of the mesonephric ducts are absorbed into the bladder
what is the trigone of the bladder formed by?
the incorporation of the caudal ends of the mesonephric ducts
what does the trigone of the bladder originate from?
mesoderm but is later covered by epithelium from endoderm
What happens to the mesonephric ducts in females? in males?
in females the ducts degenerate;
in males they form the ductus deferens and epididymis
what is the urachus? what forms it?
it is the allantois which was continuous with the bladder; it obliterates and forms the median umbilical ligament
what is exstrophy of the bladder? what is it caused by? what is it associated with?
it is when the bladder opens broadly on the abdominal wall. the lower abdominal area breaks downs as does the anterior wall of the bladder.;
it is caused by insufficient mesoderm in the anterior abdominal wall;
Associated with epispadias
What is a urachal fistula (patent urachus) caused by? what clinical symptoms does it present?
due to failure of obliteration of the urachus; causes urine to leak out at the umbilicus
what does a urachal cyst present?
blind sac connected by fibrous cords to bladder and umbilicus; may become infected and leak into umbilicus or bladder
what is a achal sinus caused by? what clinical symptoms does it present?
part of the urachus persists but is not connected to the bladder; forms a blind pouch; if infected there is DISCHARGE AT THE UMBILICUS
The cloacal membrane is divided into _____ and ____ by the urorectal septum
anal membrane and urogenital membrane
what is derived from the vesical portion of the UG sinus?
urinary bladder epithelium
the trigone of the bladder is originally derived from ______.
mesodern, from caudal ends of mesonephric ducts
the remnant of the allantois in the adult is known as the ____.
urachus
Failure of the anterior abdominal wall and anterior wall of the bladder to form is known as ____.
exstrophy of the bladder
If urine spills out at the umbilicus, you would expect ____.
urachal fistula
What does the nephrogenic cord give rise to?
kidney
what does the mesonephric duct give rise to?
ureter, male ducts, seminal vesicles
what does the paramesonephric ducts give rise to?
uterine tubes, uterus, part of vagina
what does the urogenital ride give rise to?
gonadal ridge, nephrogenic cord, mesonephric duct, paramesonephric duct
What is genetic sex defined by?
XX or XY, determined at fertilization
What is gonal sex defined by? what determines it?
either testes or ovaries will develop; depends on presence of SRY gene
what does hormonal/ductal sex depend on? what does it define?
the effect of testosterone and anti-mullerian hormone on the development of the genital ducts to either develop male ductus deferens, epididymis, and seminal vesicles, or femal uterus, uterine tubes, and vagina
what is phenotypic/genital sex defined by? what does it develop in response to?
whether the body appears male or female: the development of external genitalia, body size, hair and fat distribution; develops in response to presence/ absence of testosterone
what induces testis formation and male sexual development?
Y chromosome through its SRY gene product
what is the innate tendency of the embryo to develop as? (male or female)
female
what does the mesoderm give rise to in the male reproductive system?
gonads, genital ducts, and external genitalia except for the urogenital sinus derivatives (prostate, bulbourethral glands, urethra)
what does the urogenital sinus give rise to in males?
- bladder
- urethra
- prostate
- bulbourethral glands
what does the urogenital sinus five rise to in the female?
- bladder
- urethra
- part of vagina
- vestibule
- vestibular glands
- hymen
what does the endoderm give rise to in the male reproductive system?
UG sinus epithelium, prostate (derived from urethra)
what does the ectoderm give rise to in the male reproductive system?
navicular fossa portion of the urethra
what does the epiblast give rise to in the male reproductive system?
primordial germ cells migrating to the genital ridge from the yolk sac
Horomonal sex refers to the effects of ____ and _____ on development of the genital ducts
testosterone and AMH (Anti-mullerian hormone)
what is meant by the phrase “the embryo is bipotential” with regard to the reproductive system?
there is the potential to develop male or female structures
what is the enzyme necessary to convert testosterone to dihydrotestosterone
5-alpha reductase
where does the genital ridge appear along? as a part of what?
the medial border of the mesonephros as a part of the urogenital ridge
what do the gonads develop from?
- primordial germ cells (spermatogonia/oogonia)
- cells from proliferating coelomic epi (develop into support cells)
- underlying intermediate mesoderm (forms CT and blood vessels)
- cells derived from mesonephros (forms tubules in the testis)
ALL ARE OF MESODERMAL ORIGIN EXCEPT THE PRIMORDIAL GERM CELLS
what do the primordial germ cells originate from?
the epiblast
what is the course of travel of the primordial germ cells?
original in the epiblast then migrate from the yolk sace and enter the genital ridges
where do the primitive sex cords form?
in the indifferent gonad
where is the SRY gene activated?
in the somatic cells of the genital ridge
what must function for differentiation of the testis to occur?
SRY protein (TDF, testis determining factor)
How do the primitive sex cords form?
by the epithelium of the genital ridge proliferating and penetrating into the underlying mesoderm
what do the primitive sex cords become in the medullary region
the medullary cords aka the sertoli cells
what forms the tunica albuginea?
a dense layer of CT that separates the sex cords from the overlying epithelium
what do the outer parts of the primitive sex cords form? inner parts?
outer = seminiferous tubules inner = rete testis
what are the efferent ductules derived from?
adjacent mesonephric tubules
what do the sertoli cells produce (important for embryology) what does this secretion cause?
produce anti-mullerian hormone which induces irreversible involution of the paramesonephric ducts (mullerian ducts)
what do the fetal leydig cells produce? what does this cause?
produce testosterone which stimulates growth of the mesonephric ducts and external genitalia
What is DHT derived from? what does it cause?
derived from testosterone in the presence of 5-alpha-reductase;
important for the development of the external genitalia in the fetus (penis, scrotum, and prostate)
what depends on the DHT?
development of the penis, scrotum and prostate
when does meiosis of spermagonia pick up?
puberty
what is the processus vaginalis?
an evagination of peritoneum that accompanies the testis as they descend from the abdomen into the scrotum 7-9 months after fertilization;
FORMS THE INGUINAL CANAL
what is the gubernaculum?
a mesenchymal condensation that extends from the testis to the inguinal region. As the testis descends, the gubernaculum grows through the inguinal region to the scrotum.
Remnant in the adult is the scrotal ligament which anchors the testis to the scrotum
what does the gubernaculum remain as in the adult
Remnant in the adult is the scrotal ligament which anchors the testis to the scrotum
failure of the processus vaginalis to close provides a pathway for _________.
indirect inguinal hernia
what is cryptorchidism? what does it cause?
undescended testes;
may cause sterility because the spermatogonesis cannot occur at body temperature
where do most ectopic testes migrate to?
thigh, perineum, or anterior abdominal wall
almost all the cells of the gonad are derived from which germ cell layer?
mesoderm
in the male, the outer portion of the gonad forms the ____.
tunica albuginea
testosterone acts on the ____ ducts.
mesonephric
