Menstrual Cycle II revision Flashcards
What concentration of E2 is needed for it to exert a positive effect and for how long?
300pM for 48 hours
How long is the LH surge for?
35-48 hours
Where are LHr found on the follicle at the preovulatory stage?
Both theca and granulosa cells
How does high cAMP keep the oocyte in meiotic arrest?
Keeps maturation promoting factor (MPF) inactive
How does high cGMP keep the oocyte in meiotic arrest?
It enters oocytes from cumulus cells via gap junctions to inhibit oocyte cAMP phosphodiesterase PDE3A activity (PDE3A normally degrades cAMP)
What else besides from cAMP and cGMP keeps oocytes in meiotic arrest?
H2O2, NO, calcium
What is mucification?
Formation of unique extracellular matrix between cumulus cells from hyaluronan
Why is mucification useful?
Important for successful ovulation, ovum pick up by oviducts and penetration of sperm
Why unequal division of cytoplasm in oocytogenesis?
Need to conserve for the oocyte all the material synthesised earlier → takes fertilized zygote through growth and implantation
When does meiosis 2 finish in eggs?
After fertilisation
What does the LH surge induce?
Expression of progesterone receptor (PR) in granulosa
Luteinisation of dominant follicle cells (both granulosa and theca)
How does the progesterone inhibitor RU486 affect ovulation?
Progesterone inhibitor (RU486) suppress ovulation
Which prostaglandins increase just before ovulation?
E and F (and HETE)
What do prostaglandins do during ovulation?
Stimulate prote`olytic enzymes
What can HETEs do?
Stimulate angiogenesis and hyperemia (↑blood flow)
Ciliated cells are controlled by which hormones?
Oestrogen
What do ovulation prediction kits measure?
LH surge
How can you use E3G to help with fertility/family planning?
E3G is a urinary metabolite of oestradiol, so it helps identify days of high fertility leading up to ovulation
What hormones are produced by the corpus luteum?
Progesterone
Inhibin A
Androgens
Oestrogens
What are ovarian causes of anovulation or other disorders of ovulation?
Primary ovarian insufficiency
Disorders that prevent ovulation such as:
1) Luteinized unruptured follicle syndrome (LUF)
2) Effect of non-steroidal anti-inflammatory drugs (NSAIDs) - blocking prostaglandins
3) Polycystic Ovary Syndrome (PCOS)
Causes of luteinised unruptured follicle (LUF) syndrome
Reduction in prostaglandin synthesis/action. EVIDENCE: Patients treated with high dose prostaglandin synthetase inhibitors (eg Indomethacin) → block in prostaglandin production and follicular rupture
The lack of cytokine - Granulocyte colony-stimulating factor 3 (CSF3) - has been linked to LUF formation in infertile women. In anovulatory women, a single injection of CSF3 during late follicular phase resulted in ovulation in most of the women
