Sex Differences (2) 4

Question 1

What is the name of the characteristic posture of the female to allow mating?

Answer 1

Lordosis

Question 2

What was found in the key experiment on guinea pigs (Phoenix et al. 1959)?

Answer 2

Females treated with testosterone as embryos at both doses (high and low) showed increased frequency of mounting and decreased frequency of lordosis

But male behaviours were not affected

Question 3

What is an organising effect?

Answer 3

Exposure to hormones early in life leads to the organisation of the brain causing a change in behaviour

Exposure to androgens early in life permanently organises the brain to express male behaviour in adulthood

Question 4

Give an example of an activational effect?

Answer 4

When the males are castrated so do not show male behaviour, they are then injected with male hormones and demonstrate male behaviours

Question 5

What converts testosterone to an oestrogen in the male and female brain?

Answer 5

Aromatase enzyme

Question 6

What are brain areas regulating reproductive behaviour rich in?

Answer 6

Aromatase and oestrogen receptors

Question 7

What was found in the ovary transplant experiments by Pfeifer in the 1930s?

Answer 7

Male rats castrated at 1 and 20 days old and implanted with ovaries

Female cycles observed after early but not late castration

Thus an organisational effect was present

Question 8

What area of the brain is important in controlling the sexual behaviour of an animal?

Answer 8

The medial preoptic area (MPOA)

Question 9

What happens in mice if the female embryo is surrounded by two males compared to when it is not?

Answer 9

Females show more aggression to females, are less attractive to males and have lengthened reproductive cycles