Embryology of the Reproductive System Flashcards
(38 cards)
What happens during the process of gastrulation?
bilaminar to trilaminar structure (endo-, meso-, ectoderm)
What 3 sections of the mesoderm exist and how are they arranged?
paraxial - most medial
intermediate
lateral plate - (most lateral)
What part of mesoderm forms the urogenital system?
intermediate
Describe what is meant by cranio-caudal folding?
- Foetus folds from both top and bottom (like a scroll)
- curls into foetal position with yolk sac hanging from middle
What are the 3 segments of the urogenital system which come from the intermediate mesoderm?
Pronephros
Mesonephros
Metanephros
In which direction do the pro-, meso- and metanephros segment?
Cranial to caudal direction
What part of the 3 intermediate mesoderm segments forms the kidney?
metanephros
The mesonephros cannot produce urine as it regresses. TRUE/FALSE?
FALSE
- mesonephros is functional and can produce a small amount of urine
- joins to the cloaca which is responsible for output of developing foetus
The pronephros regresses completely. TRUE/FALSE?
TRUE
At what week does a foetus differentiate into male or female?
WEEK 7
weeks 4-6 undifferentiated gonadal proliferation
Where do the Primordial germs cells stay until migration to the intermediate mesoderm via the dorsal mesentery in weeks 4-6?
In the yolk sac
What do the Primordial germs cells do after migrating in towards the mesonephros?
- Cause proliferation of epithelium => formation of gonadal ridge
- form primitive gonad (Not M/F)
- differentiate into somatic support cells
What two ducts are involved in the formation of genitalia?
Mesonephric (Wolffian) Duct
Paramesonephric (Mullerian) Duct (formed by peritoneum infolding alongside mesonephric duct)
Which duct joins at the bottom just before attaching to the urogenital sinus?
paramesonephric duct
What transcription factor protein is responsible for Male reproductive development after the primitive gonad has been formed?
SRY protein (Sex determining region of Y) - found on short arm of Y chromosome
Describe how the primitive gonad changes to form the male reproductive organs
- Somatic support cells develop into Sertoli cells
- Primary sex cords form medullary cords
- Rete testis connect mesonephric tubules to the seminiferous tubules
- Cortex depletes and thickened layer of connect tissue forms called the tunica albuginea
What are the main functions of sertoli cells?
- stimulate formation of Leydig cells (these secrete testosterone)
- secrete AMH (antimullerian hormone)
=> causes regression of Mullerian (paramesonephric) duct
What does the mesonephric duct form into in a male foetus?
- epididymis
- vas deferens
- seminal vesicles
What hormone stimluates formation of genitalia and how is this hormone made?
Dihydrotestosterone (DHT)
5-alpha-reductase changes testosterone to DHT
What consequences can an AMH mutation cause?
No antimullerian hormone produced
=> female repro tract still develops from paramesonephric duct as it doesn’t regress
What structure is responsible for descending the testis through the inguinal canal?
gubernaculum
Why do the testis descend?
To regulate their temperature and initiate spermatogenesis
What consequence can result from the top of the scrotal cavity being open?
Indirect inguinal hernia
Does the cortex or medulla of the primitive gonad regress if the foetus is differentiating into a female?
Medulla regresses => opposite of males
If medulla regresses there can be no connection to mesonephric duct
