Embryology of the Urogenital System Flashcards
The urinary (and genital) system develops from what?
mesoderm of trilaminar disc
Intermediate mesoderm separates from lateral and paraxial mesoderm during folding and forms what?
urogenital ridge
In regards to mesonephros, during the 4th week, what develops?
A second primitive kidney; functional glomeruli; mesonephric tubules; and mesonephric duct opens into cloaca
Mesonephros are present and functional from week ___ to week ___
6-10
After week 10, mesonephros degenerates except for:
the duct system - contributes to part of the male genital system
some vestigial structures in the female
Steps in Renogenesis involve a process of reciprocal induction, which is ___ ___ dependent
retinoic acid
In regards to Renogenesis, what type of patterning establishes a “renogenic” region within th intermediate mesoderm in the tail of the embryo?
cranial-caudal
The renogenic mesoderm is the ___ ___
metanephric blastem
In Renogenesis, the metanephric blastema secretes growth factors that include growth factors that induce growth of the ___ ___ from the caudal portion of the mesonephric duct
ureteric bud
In renogenesis, the ureteric bud proliferates and responds by secreting growth factors that stimulates proliferation and then differentiation of the metanephric blastema into what?
glomeruli and kidney tubules
In renogenesis, pertuberations in any aspects of inductive events may cause what?
inhibition of ureteric bud growth and renal hypoplasia or agenesis
List uteric bud derivatives in order that they develop
collecting tubules/ducts -> minor calyces -> major calyces -> renal pelvis -> ureters
Blood plasma from glomerular capillaries begins to be filtered by what week?
10
Urine is produced but the primary function is not to clear waste. What is the primary function at this time?
supplement production of amniotic fluid
What is oligohydraminos?
insufficient amount of amniotic fluid
What indicates bilateral renal agenesis or urethral obstruction?
oligohydraminos
Kidneys are formed in pelvis but ascend to lumbar region with progressive revascularization from which two sources?
common iliac & aorta
Aberrant renal vessels enter the kidney independently from what?
primary renal vessels
True or false?
Aberrant renal arteries that enter the upper or lower poles of the kidney may pose problems
true
Aberrant arteries to the inferior pole of the kidney may be the cause of obstruction of the ureter and may cause what?
an intermittent or continous obstruction to urinary drainage from the renal pelvis
Renal fusion prevents what?
normal rotation
Renal fusion causes abnormal blood supply in what area?
usually from middle sacral or common iliac arteries
What is the name of the most common fused kidney?
horseshoe kidney
This type of renal tumor usually affects children under the age of 5 and is caused by mutations in the WT1 gene
Wilms’ tumor
In regards to development of the urinary bladder, the cloaca is divided by what?
the urorectal septum
The dorsal portion of the cloaca develops into what?
the rectum and anal canal
The ventral portion of the cloaca develops into what?
the bladder and urogenital sinus which will give rise to the bladder and lower urogenital tracts
The triangular region of the incorporated mesonephric duct incorporated in the bladder wall forms the ____
trigone
What occurs during a urachal fistula
bladder is continuous superiorly with allantois
Remnants of the tracheal lumen may give rise to urachal ___, which usually present as an abdominal mass
cysts
The genotype of the embryo is established when?
at fertilization
True or False?
From weeks 1-6, the embryo remains in an undifferentiated state
true
Phenotypic sexual differentiation occurs at what week?
week 7
male and female external genitalia can be recognized at what week?
week 12
phenotypic differentiation is complete at what week?
week 20
Fetal sex of male is encoded on which gene on the Y chromosome?
SRY
Synthesis of SRY protein triggers what?
male development
If SRY is not expressed, what occurs?
female development
In regards to development of genital ducts, how many pairs of ducts are present in both sexes?
two
Both pairs of ducts are present during what stage of development
indifferent stage
In the male, which ducts play the most important role?
the mesonephric ducts
In the female, which ducts play the most important role?
paramesonephric
The gonads develop from what 3 tissues?
epithelium of intraembyronic coelom, intermediate mesoderm, and primordial germ cells
Pimordial germ cells from mesoderm of yolk sac invade the dorsal mesentery and migrate where?
urogenital ridges
What are aggregates of supporting cells (hormone secreting cells) of the gonads
primary sex cords
In regards to external genitalia, what is the phallus in males and females?
males: penis
females: clitoris
In regards to external genitalia, what are the urogenital folds in males and females?
males: shaft of penis
females: labis minoris
In regards to external genitalia, what are the genital swellings in males and females?
males: scrotum
females: labis majora
In regards to internal ducts, partial or total atresia of distal portion of both ducts can result in what?
cervical or vaginal atresia
46, XY can have a presistence of paramesonephric ducts if the circulating levels of ___ are low or there is an abnormal response to normal ___
AMH; AMH
Failure of the paramesonephric ducts to develop occurs in
mullerian agenesis
note: also called MRKH
In regards to external genitalia, what is incomplete fusion of the urethral folds called?
hypospadias
Females with severe adrenal hyperplasia have ambiguous genitalia at birth due to what?
excess adrenal androgen production in utero
Name the following disorder:
x-linked disorder in which receptors remain unresponsive to androgens; external genitalia are feminine but internally possess non-functioning testes; at puberty, secondary female sexual characteristics may appear due to estradiol from testosterone aromatizaiton
Androgen Insensitivity Syndrome
Name this condition:
autosomal recessive condition resulting in the inability to convert testosterone to the more physiologically active dihydrotestosterone; often misdiagnosed as AIS
5-alpha reductase deficiency
