Folliculogenesis & Oogenesis Flashcards
(34 cards)
When do oogenesis and folliculogenesis start? when are final stages
Starts at sexual differentiation and final stages in adult life during follicular phase of ovarian cycle
Where does oogenesis begin?
in fetal ovary when primordial germ cell enter gonad and become oogoniaa
What is difference between male female egg formation
in female, all of the primary oocytes formed b4 burned. in fetal development
What are the fates of a primordial follicle. When does first recruitment happen
- remain quiescent
- Resume development
- undergo atresia
First recruitment at puberty. and in female come at steady trickle
Name three phases of follicular genesis
- Preantral
- Antral
- Preovulatory
What type of follicule is selected for ovulation.
The tertiary follicle which. and the dominant one is probably the biggest due to more R
What creates zone Pullucida
the oocyte secretes glycoproteins to create thin translucent layer. =ZP
What blocks communication with oocyte and granulose cells? How do granulose cells overcome this
the ZP blocks communication. Cytoplasm britches (Gap junctions) allow for communication
How do thecal sells develop from prenatal to antral
How do granulose cells develop
theca interna- inner glandular, highly vascular
Externa - fibrous capsule layer
granulosa - continue proliferation to increase follicular size
What make up follicular fluid ? What secretes fluid? what stage of folliculogensis
Granulose cells proliferate and secrete follicular fluid in the pre antral to antral phase,
Made of: mucopolysaccharides and serum (ions) = droplets
Corona Radiata (cumulus). what is it connected to
forms around the ZP during prenatal to antral phase. it’s like derived from the “mural” granulosa cells.
anchors (cumulus) from mural granulosa to corona radiata which is around ZP
Draw antral phase
Go
Why do you have PREANTRAL development previous to puberty
There is no required input from gonadotropins / ovarian hormones to initiate primordial follicular development follicular.
This is still before puberty so since it will remain in preantral, they will gounder atresia b4 puberty
When / why do a human/rat need gonadotropin support in follicular growth
Need it to develop the fluid filled antrum and go from pre antral to antral phase. Humans- when antral follicle is greater than 2mm (tertiary). Rat- Late in preantral
What does atresia involve. How do we know atresia is occurring ?
- Reduced protein synthetic activity
- accumulation of lipid droplets
- pyknotic nuclei
Pyknotic nuclei
(atresia) nucleus shrinks and chromatin condense to solid structureless mass
How do follicles prevent atresia
FSH LH Receptors appear in late preantral/ antral phase.
FSH sufficient ; LH = antral expansion
Therefore gonadotrophins stimulate antral growth in prenatal follicles
Explain the two-cell theory.
LH stimulated interna theca cells recruit cholesterol or acetate and produce androgen(T)
Androgen converted by FSH stimulated granulosa cells.
Explain intrafollicular hormones in antral phase
FSH+androgens stimulate proliferation of granulosa cells = follicular growth
Also increase aromatase activity in granulosa cells
estrogen has positive feedback to stimulate granulosa proliferation
How does follicle induce estrogen surge ? What does it provide for?
the positive feedback of estrogen from granulosa cells to initiate even more estrogen production/ granulosa proliferation provides estrogen surge for most advanced follicle
What role does LH play in pre ovulation phase?
FSH+Estrogen increased LH R on granulosa cells . this is required bc inhibin will soon decrease FSH. without LH surge, = atresia
What produces in inhibin
Granulosa cells which have negative feedback on FSH
Define Deviation
The follicle with the largest #LH/FSH R and therefore most amount of granulosa cells will be selected as dominant follicle as it has the most chance at responding to lower levels of FSH due to increased Estrogen from granulosa cells
LH Surge affects follicles in two ways
- causes oocyte + Follicle changes resulting in oocyte expulsion
- follicle becomes CL
