15. Development of Reproductive System Flashcards
When do the indifferent gonad first show up
Week 5
End up in yolk sac wall after gastrulation and body folding
Where does the primitive gonadal ridge develop
T10 near primitive mesonephric kidney
What structures are derived from the Mesonephric duct (Wolffian)
Epididymis
Vas deferens
Seminal vesicle
Ejaculatory duct
What structures are derived from the Paramesonephric duct (Mullerian)
Oviduct
Uterus
Upper vagina
What does the SRY gene do
Promote male development and differentiation
- activate SOX9 to activate Anti-Mullerian Hormone (AMH)
- Mullerian ducts regress in weeks 8-10 in presence of AMH
When do Leydig cells begin releasing/making testosterone
week 8
What are the origins of the seminal vesicle, prostate gland and bulbourethral glands
Seminal- buds from mesonephric duct
Prostate- buds from endoderm of urogenital sinus in region of pelvic urethra (week 10)
Bulbourethral- from endodermal buds
What is the genital tubercle in terms of male external genitalia
Ectodermal-covered mesodermal swelling responsible for the phallic portion of the urogenital plate
-DHT drives the lengthening and also fusion of labioscrotal swellings to form scrotum
What are hypospadia and Epispadia
Hypospadia- caused by failure of urethra folds to close properly leading to urethral opening on ventral side
Epispadia- urethra opens on dorsal side of penis (associated with exstrophy of bladder)
Female genitalia develops in absence of SRY and the presence of a pro-female gene
WNT-4
What is the function of FOXL2 in female differentiation
FOXL2 continually suppresses SOX-9 which maintains female gonads
- no sertoli cells means no AMH (persistence of Mullerian duct)
- no leydig cells means loss of wolffian duct
How does the uterus form
Fusion of Paramesonephric ducts around weeks 9-10
-Uterine tubes are unfused superior portions of the paramesonephric ducts
What is didelphys
Double uterus
What is responsible for vaginal formation
Lengthening of sinuvaginal bulb (endodermally derived)
-bulb is eventually canalized
In female external genitalia development what happens in the absence of DHT
- no lengthening of genital tubercle
- no fusion of urogenital folds or labioscrotal swellings
How is the broad ligament formed
-Upon completion of uterus and oviduct formation, the remaining tissue thins forming a double fold of peritoneum (broad ligament) supporting the uterus and ovary
In the female what do the superior and inferior gubernaculum become
Superior- round ligament of ovary
Inferior- round ligament of uterus
What can cause a male XY genotype to have testis but the phenotype is female
(MALE DSD)
- Inadequate testosterone synthesis
- Androgen insensitivity syndrome
- 5a-reductse deficiency
- Mutations in AMH or AMH receptor
What is Androgen Insensitivity Sydrome
loss of function androgen receptor
- have testes but no spermatogenesis
- produce AMH so paramesonephric system is suppressed, absence of uteres or uterine tubes and vagina is short and ends blindly
What is 5a-reductase Deficiency
- Normal testis and duct system develop as there is AMH and tesosterone
- Underdeveloped male external genitalia dependent on DHT
What is congenital adrenal hyperplasia
-Most common cause of female sexual ambiguity due to mutations in genes involved in adrenocortical steroid biosynthesis (21-hydroxylase)
What is an Ovotesticular disorder
-Have both testicular and ovarian tissue and ambiguous external genitalia
Causes:
-Translocation of piece of Y chromosome onto X chromosome
Subset of cells may have mutation in Y chromosome
-Anomaly in sex determination/differentiation of primary germ cells
