Menstrual Cycle I

Question 1

What is the key requirement to maintain the HPG axis?

Answer 1

Pulsatility of release of GnRH and gonadotrophins

Question 2

The length of a menstrual cycle is..

Answer 2

period of time between start of menstrual bleeding (day 1) in one cycle

—>

the onset of menses of the next cycle.

Question 3

Median duration of Menstrual cycle is how many days?

Answer 3

28 days with most cycles between 25-30 days

(Luteal phase is fixed)

Question 4

Menstruation lasts… (how many days?)

Answer 4

3-8 days

Question 5

Polymenorrheic

Answer 5

MC<21 days

Question 6

Oligomenorrheic

Answer 6

MC>35 days

Question 7

Which steroids are made where?

Answer 7

Question 8

The Menstrual Cycle (the follicular stages)

Answer 8

Question 9

HPO axis

Answer 9

Negative & positive feedback
Follicular phase

Negative feedback
luteal phase

Question 10

Inhibin is produced by..

Answer 10

Testis (Sertoli cells)
&
Ovary (Granulosa cells)

Question 11

Both forms of Inhibin specifically suppress..

Answer 11

FSH secretion by pituitary without affecting LH secretion

Question 12

Activins from where _______ stimulate what?

Answer 12

Activins from follicular fluid stimulate FSH secretion

Question 13

Follistatin - where what does it generally known for?

What does it specifically do?

Answer 13

Another FSH-suppressing protein from follicular fluid.

Binds activin with high affinity » neutralizes FSH-stimulating ability of activins

Question 14

Effect of Inhibin/Activin sub-types (table)

Answer 14

Question 15

Activins correlation with FSH rise in Early follicular phase of MC

Inhibin with FSH fall in Late Follicular Phase of MC

Answer 15

levels of activin high at start of MC (EFP) but fall by luteal phase of MC,

whereas inhibin start to rise in LFP of MC and peak in luteal phase.

Question 16

AMH is a _______ and also a member of the ___________

Answer 16

AMH is a glycoprotein and also a member of the TGFβ superfamily

Question 17

When is AMH expressed in Males?

What does it cause?

How?

Answer 17

In males expressed from week 8 of development

causes regression of the Müllerian ducts by a wave of apoptosis.

Question 18

AMH is expressed by which cells?

When do levels peak?

Answer 18

Ovarian granulosa cells.

Levels peak in selectable follicles (large preantral and small antral follicles) » then decrease.

Question 19

AMH has 2 windows of action on folliculogenesis:

Answer 19

Inhibits transition from primordial –> primary follicles

Inhibits FSH-dependent cyclical recruitment of follicles by inhibiting FSH-stimulated aromatase and FSH receptor expression.

In the normal cycle would act to prevent over-recruitment of growing follicles

Question 20

FSH threshold hypothesis

Answer 20

Raised FSH present a “window” of opportunity

One follicle from the group of antral follicles in either ovary is just at the right stage at the right time….

This becomes the dominant follicle which survives fall in FSH and goes onto ovulate

Known as “selection”

Question 21

What causes FSH levels to fall to prevent further follicle growth?

Answer 21

Oestradiol levels rise reinstating negative feedback at pituitary

Question 22

Once primordial follicles start growing and progressing, they become ______ independent

Answer 22

Once primordial follicles start growing and progressing, they become FSH independent

Question 23

How does the dominant follicle survive the fall in FSH?

Answer 23

As FSH falls, LH increases.

Dominant follicle acquires LH receptors on granulosa cells.

Other follicles do not, so they loose their stimulant and die.

Question 24

Which type of receptors are present on Granulosa cells?

Answer 24

Have FSHRr, then LHr acquired from mid-follicular phase onwards.

Question 25

What steroids are produced as a consequence in the granulose cells?

Answer 25

FSH drives Oestrogen production in follicular phase and

LH drives progesterone production in luteal phase.

Question 26

Which type of receptors are present on Theca cells?

Answer 26

Always LHr, NEVER FSHr

Question 27

What steroids are produced as a consequence in the theca cells?

Answer 27

LH drives androgen and progesterone production from theca

Question 28

Inhibin B levels in follicular phases

Answer 28

Highest in early-mid Follicular Phase (ratio of activin: inhibin)

and declines in Late Follicular Phase (small peak at LH surge)

ZERO in luteal phase.

Question 29

Inhibin A levels in follicular phases

Answer 29

Increases in late Follicular Phase with highest levels in luteal phase (being made by Corpus Luteum which contributes to inhibition of FSH in this phase.

The dramatic decline in Inhibin A at the end of the luteal phase allows for increase in FSH.

Question 30

(picture to review)

Characteristic changes occur in reproductive tract tissues due to varying concentrations of E2 & P in different parts of MC:

Endometrium
Oviduct/Fallopian tubes
Cervix
Vagina - changes in vaginal epithelial cells

Answer 30