The Ovary: Ovarian Follicle Development Flashcards
What is a PGC (primordial germ cell)
This is the cell before it goes down either male or female pathway
When the PGC get to the female gonad they become what?
Oogonia
When mitotic division stops and meiosis starts the oogonia is called what?
Oocyte
What is an oocyte called after ovulation but before fertilisation?
Egg
In the developing fetal ovary what are oogonia surrounded in?
Somatic cells which form nests
What are found within the stromal nests in a developing ovary?
There are cysts of germ cells with cytoplasmic connection to each other due to incomplete cytokinesis - this means there is cytoplasmic movements
What do the mesonephrones secrete to tell the ooconia to stop undergoing mitosis and to start meiosis?
Retinoic acid (in males this would just be ignored)
What stage does retinoic acid happen?
Fetal ovary stage
Retinoic stops mitosis which means what?
There will be no more new oogonia (she can only lose them).
Can you make new germ cells from ovary in vitro?
Yes - but you cant do it in the body
How does mioisis work in females?
One cell replicates its DNA. This is now called an oocyte and is maintained in meiotic arrest.
Eventually it will ressume and undergo meiotic division. The DNA split leaving a cell with 2 chromosomes and a polar body with 2 chromosomes
The 2nd meiotic then occurs and you are left with one cell with 1 chromosome and 2 polar bodies.
How many haploid germ cells do you get from males?
4
How many germ cells do you get from female meiosis?
1 and 2 polar bodies
When do oocytes stay in meiotic arrest?
From when it first becomes a follicle (before birth) and comes out of it after ovulation.
What happens after oocytes begin meiosis and are still surrounded by the nest?
Somatic cells now invade cysts and surround individual oocytes
Somatic cells invading cysts and surrounding oocytes are called primordial follicles. What are primordial follicles?
Oocytes surrounded by single layer of granulosa cells (this is accompanied by lots of cell death).
What also forms between oocyte and granulosa cells in a primordial follicle?
Zona pellucida
When do follicles form in humans?
Just around mid pregnancy
Once a follicle formation is complete do the ovary have an endless pool?
No
Are primordial follicles able to stay in a resting state until ovulation (which could be around 45)?
Yes