2.3 The Biology of controlling fertility

Question 1

Cyclical Fertility

Answer 1

Women show Cyclical Fertility which leads to a fertile period. This is because women are only fertile for a few days during each menstrual cycle.

Question 2

Continuous Fertility

Answer 2

Men show Continuous Fertility as they continually produce sperm in their testes.

Question 3

Identifying the Fertile Period

Answer 3

A woman’s body temperature rises by around 0.5°C after ovulation and cervical mucus becomes thick and watery during fertile period.

Question 4

Ovulatory Drugs

Answer 4

Ovulatory drugs (which stimulate ovulation) in overcoming infertility will either prevent the negative feedback effect of oestrogen on FSH secretion OR mimic the action of FSH and LH.

Question 5

Super Ovulation

Answer 5

Ovulatory drugs can cause super ovulation that can result in multiple births or be used to collect ova for IVF programmes.

Question 6

Artificial Insemination

Answer 6

When several samples of semen are collected over a period of time. This sample is then inserted into the female reproductive tract by means other than sexual intercourse.
Artificial insemination is useful when the male has a low sperm count. If he is sterile, a donor may be used to provide semen.

Question 7

Intra-Cytoplasmic Sperm Injection (ICSI)

Answer 7

Can be used if mature sperm are
defective or very low in number. The head of the sperm is drawn into a needle and injected directly into the egg to achieve fertilisation.

Question 8

PGD

Answer 8

Can be used before transferring the fertilised eggs to the uterus during IVF to identify single gene disorders and chromosomal abnormalities.

Question 9

Stages of In-Vitro Fertilisation (IVF)

Answer 9

1. The female is given ovulatory drugs to stimulate super ovulation and these eggs
   are surgically removed from the ovaries.
2. The eggs are then mixed with sperm in a culture dish to allow for fertilisation (if
   needed ICSI can be used here).
3. The fertilised eggs are then incubated until they have formed at least 8 cells and are then transferred to the uterus for implantation.

Question 10

Physical Methods of Contraception

Answer 10

• barriers such as condoms
• intra-uterine devices (which are placed in the uterus and prevent an egg from implanting)
• sterilisation procedures such as a vasectomy (cutting and tying of sperm ducts) or tubal ligation (cutting and tying of oviducts.

Question 11

Chemical Methods of Contraception

Answer 11

• the oral contraceptive pill which contains a combination of synthetic oestrogen
and progesterone that mimics negative feedback preventing the release of FSH and LH
from the pituitary gland.
• the progesterone-only (mini) pill which causes thickening of the cervical mucus.
• The morning-after pill which prevents ovulation.