Int 1: Fertilisation, Assisted Reproduction and Contraception

Question 1

Order the following parts of an oocyte from outer most to inner most:

• 2nd Meiotic metaphase spindle
• 1st Polar body
• Perivitelline space
• Cortical granules
• Ooleuma
• Zona pellucida

Answer 1

1. Zona pellucida: Outer most membrane
2. 1st Polar body
3. Perivitelline space
4. Ooleuma
5. Cortical cells
6. 2nd meiotic metaphase spindle

Question 2

What are 3 functions of the Zona pellucida

Answer 2

• Prevents polyspermy
• Mediates specific recognition
• Protects preimplantation embryo from reabsorption

Question 3

What are the 3 main components of a spermatozoon?

Answer 3

• Acrosome
• Nucleus
• Centriole

Question 4

After the spermatozoon has hit the egg, the acrosome reaction, stimulated by a)__________ occurs releasing proteolytic enzymes such as b)__________

• Progesterone
• Acrosin

Answer 4

a) Progesterone
b) Acrosin

Question 5

What is the measure of a) fecundity and b) fertility?

Answer 5

a) Measures capacity to conceive and have live birth
b) Actual outcome of reproductive success

Question 6

What is one route of sterilisation for men and one for women

Answer 6

MEN:
- Vasectomy: Removal of part of the vas deferens. Sperm production continues but passage is blocked

WOMEN:
- Tube ligation: Fallopian tubes clipped

Question 7

Hormonal methods manipulate the WHAT axis to prevent ovulation. And what is the primary hormone that stimulates release of LH and FSH?

Answer 7

HPO axis
Gonadotrophin

Question 8

What are the primary functions, effectiveness and side effects of the following hormonal contraception methods:

a) Hormonal implant
b) The Pill

Answer 8

a)
Function: Inhibit ovulation, secondary effect on cervical mucus
Effectiveness: Very effective
Side effects: Irregular bleeding

b)
Function: Progesterone supresses ovulation and Oestrogen just backs it up
Effectiveness: Fail rate = 9-12%
Side effects: Weight gain, acne, headaches

Question 9

Why is copper used as a contraceptive in intrauterine devices?

Answer 9

Copper is cytotoxic to sperm

Question 10

What are some other methods of contraception?

Answer 10

• Hormonal injection (Same as the pill)
• Intrauterine devices (copper / hormonal version)
• Morning after pill (LH surge delaying ovulation)
• Copper IUD

Question 11

There are also contraceptive vaccines to prevent fertilisation:
- Long term
- Lack of endocrine side effects
- GnRH - not good
- hCG
- Zona pellucida proteins ZP3

Question 12

NOTE:

• Secretory endometrium is found in the luteal phase of the cycle
• There is an FSH surge at ovulation
• GnRH works through the LH receptor
• Progesterone is measured to ensure the ovaries are working properly
• 85% of couples will achieve pregnancy within 1 year (67% in 6 months)