Menstrual Cycle II revision

Question 1

What concentration of E2 is needed for it to exert a positive effect and for how long?

Answer 1

300pM for 48 hours

Question 2

How long is the LH surge for?

Answer 2

35-48 hours

Question 3

Where are LHr found on the follicle at the preovulatory stage?

Answer 3

Both theca and granulosa cells

Question 4

How does high cAMP keep the oocyte in meiotic arrest?

Answer 4

Keeps maturation promoting factor (MPF) inactive

Question 5

How does high cGMP keep the oocyte in meiotic arrest?

Answer 5

It enters oocytes from cumulus cells via gap junctions to inhibit oocyte cAMP phosphodiesterase PDE3A activity (PDE3A normally degrades cAMP)

Question 6

What else besides from cAMP and cGMP keeps oocytes in meiotic arrest?

Answer 6

H2O2, NO, calcium

Question 7

What is mucification?

Answer 7

Formation of unique extracellular matrix between cumulus cells from hyaluronan

Question 8

Why is mucification useful?

Answer 8

Important for successful ovulation, ovum pick up by oviducts and penetration of sperm

Question 9

Why unequal division of cytoplasm in oocytogenesis?

Answer 9

Need to conserve for the oocyte all the material synthesised earlier → takes fertilized zygote through growth and implantation

Question 10

When does meiosis 2 finish in eggs?

Answer 10

After fertilisation

Question 11

What does the LH surge induce?

Answer 11

Expression of progesterone receptor (PR) in granulosa

Luteinisation of dominant follicle cells (both granulosa and theca)

Question 12

How does the progesterone inhibitor RU486 affect ovulation?

Answer 12

Progesterone inhibitor (RU486) suppress ovulation

Question 13

Which prostaglandins increase just before ovulation?

Answer 13

E and F (and HETE)

Question 14

What do prostaglandins do during ovulation?

Answer 14

Stimulate prote`olytic enzymes

Question 15

What can HETEs do?

Answer 15

Stimulate angiogenesis and hyperemia (↑blood flow)

Question 16

Ciliated cells are controlled by which hormones?

Answer 16

Oestrogen

Question 17

What do ovulation prediction kits measure?

Answer 17

LH surge

Question 18

How can you use E3G to help with fertility/family planning?

Answer 18

E3G is a urinary metabolite of oestradiol, so it helps identify days of high fertility leading up to ovulation

Question 19

What hormones are produced by the corpus luteum?

Answer 19

Progesterone
Inhibin A
Androgens
Oestrogens

Question 20

What are ovarian causes of anovulation or other disorders of ovulation?

Answer 20

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)

Question 21

Causes of luteinised unruptured follicle (LUF) syndrome

Answer 21

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