Menstrual Cycle

Question 1

What are the 3 stages of the ovarian cycle?

Answer 1

follicular phase
ovulation
postovulatory/ luteal phase
(average duration is 28days)

Question 2

What is needed for a normal menstrual cycle?

Answer 2

1. An intact hypothalamo-pituitary-ovarian endocrine axis
2. presence of responsive follicles in the ovaries
3. a functional uterus

Question 3

How long is the luteal phase?

Answer 3

14 days
(follicular phase may legthen- prolonged cycle)

Question 4

What controls follicular maturation and ovulation?

Answer 4

Hypothalammo Pituitary Ovarian axis (HPO)

Question 5

What does the hypothalamus secrete to act on the pituitary gland?

Answer 5

GnRH

secreted in a pulsitile manner (every 90 mins)

Question 6

What is the action of GnRH on the anterior pituitary?

Answer 6

Acts on pituitary gonadotrophins

stimulates synthesis and release of FSH and LG

Question 7

What is the role of FSH?

Answer 7

A glycoprotein
stimulates follicular maturation during follicular phase
stimulates steroid hormone secretion (oestrogen) by the granulosa cells of the mature ovarian follicle

Question 8

Role of LH?

Answer 8

contributes to steroidogenesis
LH mid-cycle surge is essential in ovulation
production of progesterone by the corpus luteum is influenced by LH

Question 9

Role of LH and FSH in the follicular phase (days 1-8)

Answer 9

FSH and LH levels are relatively high
This is triggered by fall of oestrogen at end of last cycle
Stimulate the develpoment of 10-20 follicles- full maturation

Question 10

What is the antrum?

Answer 10

a fluid-filled central cavity
as follicle increases in size fluid appears among granulosa cells and becomes confluent
(days 9-14)
transforms primary follicle into Graafian follicle