Origin and Development of germ cells in male and female Flashcards
What are the earliest germ cells called?
Primordial germ cells
Where are Primordial germ cells originated from?
Yolk sac
Where do Primordial migrate to from the yolk sac?
through hind gut to genital ridge
What tissue does primordial cells migrate through?
Mesentary tissue
Where do gonads develop?
Genital ridge
Where does the kidney develop from?
Mesonephros
What cells do primordial cells associate with at the genital ridge?
Pre-sertoli cells (somatic cells)
In the male genital ridge how do the somatic cells align themselves?
Align in cords and develop into semineferous hoops to tubules as they grow
What cells settle on the tubule wall first?
PGC primordial germ cells then somatic cells
What are the male and female processes called?
Spermatogenesis
Ovagenesis
Where are the Spermatogonia developed in males?
Outside the blood testes barrier BTB
In females what is different in the associate with somatic cells?
Stop in cortical region from the ridge and form a layer around each germ cell
What is BTB?
Blood testes barrier - tight junctions that hold the cell together, it is impermeable so cells have to go through cells
Why is BTB important?
The immune system develops very early, so post puberty cells express new proteins that immune would think are foreign bodies
What does spermatogonia develop in regards to BTB?
develop germ cells behind the barrier
How do PGC’s proliferate and what in to?
Mitosis and into gonocytes
What happens to gonocytes?
Proliferate by mitosis and develop into pro-spermatogonia (end of foetal stage)
What happens to early spermatogonia and what do they acquire?
Become stem cells and acquire self-renewal capacity
What effects can Gonocytes not proliferating cause?
if stuck in cell cycle arrest then remain in situ, can randomly activate and proliferate to form tumours
What happens to the spermatogonia sitting on tubule wall?
Embeds into sertoli cells with tight junctions forming BTB
Where and what does spermatogonia develop into?
change to spermatocytes from cytoplasm to the lumen where they develop
Why is a large stem cell pool good in primates?
develops same number as germ cells and so greater human resilience
What division produces spermatocytes?
Peri-natal spermatogonial division (2nd mitotic division)
Where do spermatocytes arrest in?
Prophase of 1st meiotic division
