Lecture 25

Question 1

What are the two main functions of the ovaries?

Answer 1

1. Formation, development and release of the ovum 2. Synthesis and secretion (oestrogens and progestogens) - steroid hormones that orchestrate the entire cycle

Question 2

What are the two types of ovary support cells that will be present?

Answer 2

granulosa cells on the inside and theca cells on the outside

Question 3

Name the following structures:

Answer 3

1. Theca cells
2. Granulosa cells
3. Oocytes
4. Stroma
5. Ovarian surface

Question 4

When would you be likely to observe a corpus leuteum?

Answer 4

After a recent ovulation event has occured

Question 5

What class of hormones regulated ovarian developement

Answer 5

gonadotropins

Question 6

What are the four main steeps that are involved in follicular developement?

Answer 6

1. Initial recruitement of the follicle occurs
2. FSH and LH from the anterior pituaritary lead to the growth and multiplication of the granulosa and theca cells
3. Whether a follicle can respond depends on whether it has receptors or not
4. Growing follicles create a negative feedback loop for the pituaritary and the hypothalamus

Question 7

Describe the process of folliculogenesis:

Answer 7

1. Pool of primordial follicles
2. Committed follicles - point of no return
3. FSH- responsive follicles whereby it influences developement
4. Low FSH causes atresia (death) the point of no return where the follicle is not able to go back
5. Dominent follicle produces inhibin that stops the other follicles from developing
6. Means that only one dominent follicle is able to exist

Question 8

What are the three main types of ovarian hormones that are produced and name the most common type of each that are present?

Answer 8

1. Oestrogens- oestrodiol 17b
2. Progestagens- progestorone
3. Androgens- DHEA

Question 9

What is the main type of non-sterioidal hormone?

Answer 9

Inhibin

Question 10

What is the function of inhibin?

Answer 10

Negative feedback system ensuring that only dominent follicles develop that high numbers of LH and FSH receptors

Question 11

What is the main function of progesterone?

Answer 11

Supporting/ maintaining pregnancy

Question 12

What is the process of ovulation?

Answer 12

A surge of leutenising hormone leads to ovarian follicle rupture that is gathered by the fimbria and then enters the oviduct. The leutensing hormone activates collagenase which then weakens the connective tissue in the ovary. After the egg release the structure is now called the corpus haemorrhagicum.

Question 13

How does the developement of the endocrine actions of the corpus leuteum occur?

Answer 13

1. Granulosa and the Theca cells invade the corpus haemorragicum and the differentiate into luteal cells
2. LH and prolactin is luteotrophic (stimulated the growth and the developement of the CL)
3. CL then produces testosterone

Question 14

What are the actions of progesterone?

Answer 14

• Hypertrophy + vascularisation of uterine lining + glands
• Decreases uterine motility
• Negative feedback on GnRH surges, so follicles do not mature and ovulate

Question 15

Briefly explain the process of leutolysis:

Answer 15

When an animals is not pregnant prostaglandin is released from the uterus. The main prostaglandin affecting the reproductive system is PGF-2 Alpha that leads interferes with the CL blood supply inhibiting progesterone production. Lutolysis must not be maintained from pregnancy so PGF-2 Alpha levels need to be maintained below the critical level. Signal molecules from the embryo lead to decreased levels of PGF-2 alpha meaning no leuteolysis occurs.

Question 16

Briefly explain how the resumption of cycling occurs:

Answer 16

If the animal is not pregnant at luteolysis this will lead to the removal of progesterone inhibition on GnRH leading to increased gonadotropin stimulation of follicular growth. Ostrodiol leads to increased GnRH surge (LH and FSH cause maturation of the next follicle).