Embryology of Reproductive System Flashcards
Where is the testis-determining factor?
on the short arm of the Y chromosome
What makes the genital ridges?
germ cells migrate to the posterior wall via dorsal mesentery and induce coelomic epithelium to form sex cords that proliferate creating the genital ridges
What 2 parts make up the sex cords?
- Medullary region
2. cortical region
What do sex cords become in males vs females?
males=sertoli cells of germinal epithelium in seminiferous tubules
females=ovarian follicles
Can sex cords develop without germ cells?
NO! and without sex cords there will be no germ cell maturation
What is present at the end of the indifferent stage?
paramesonephric ducts, mesonephric ducts, primary UG sinus, and gonads
What genes are involved in sertoli cell production?
On the Y chromosome is the SRY gene that up regulates SF1 which acts through SOX9 in the sex cords causing them to differentiate into sertoli cells
What do sertoli cells produce?
anti-mullerian hormone
what happens if SRY is not present?
then we get differentiation into oogonia and follicle cells leading to a lack of sertoli cells and no anti-Mullerian hormone
What genes are involved in early ovary development?
WNT4, DAX1 and FoxL2.
- WNT4 is produced by the mesonephric mesenchyme and coelomic epithelium and up regulates Dax1 which causes the cortical sex cords to differentiate into oogonia and follicle cells. FoxL2 is expressed in pregranulosa and granulosa cells
What does AMH cause?
degeneration of paramesonephric ducts and cells in the gonadal ridge to become leydig cells which produce testosterone dihydrostestosterone.
What causes production of sex determination (ducts) in males?
AMH and testosterone (mainly T)
What gives rise to the male genital duct system?
mesonephric duct. If AMH is present, paramesonephric duct degenerates. AMH also causes development of leydig cells which make testosterone that binds to receptors in the mesonephric duct and initiates its development into male genital duct system
In the male, what is the role of DHT?
prostate development and external genitalia into a penis and scrotum
What gives rise to the female genital duct system?
paramesonephric duct. In absence of AMH, mesonephric duct degenerates because of lack of testosterone. Paramesonephric develops into the uterine tubes, uterus, cervix, and upper 1/3rd of the vagina with the help of estrogen from maternal adrenal and placenta
What does the uterovaginal canal give rise to in the female?
uterine tubes and upper 1/3 of the vagina
What does the UG sinus give rise to in the female?
pelvic urethra
What does the pelvic urethra give rise to in the female?
sinovaginal bulbs that develop into lower 2/3 of the vagina
What does the genital tubercle give rise to?
Male: glans and shaft of penis
Female: glans and shaft of clitoris
What does the def. UG sinus give rise to?
Male: penile urethra
Female: vestibule of vagina
What do the urethral folds become?
Male: penis
Female: labia minora
What do the labioscrotal folds become?
Male: scrotum
Female: labia majora
What is hypospadias?
When the urethral folds fail to fuse in the midline so the urethra exits the penis midshaft.
What is the time difference in phenotypic sexual differentiation vs brain sexual differentiation?
Phenotypic: first 2 months of pregnancy
Brain: 2nd half of pregnancy
