Lecture 7

Question 1

What is meant by the word sex?

Answer 1

• Gender identity
• biological sex
• sexual orientation

Question 2

What are the 7 types of biological sex differences?

Answer 2

1. Chromosomal sex
2. gonadal sex
3. internal reproductive system
4. external reproductive system
5. pubertal sex changes
6. brain sex
7. behavioural and ‘cognitive’ sex

Question 3

What are the factors controlling the development of female sex organs?

Answer 3

• Female = XX = Primordial gonads develop into ovaries

If hormones occur:
- Müllerian system develops into fimbriae, fallopian tubes, uteras, inner vagina
OR
- Primordial external genitalia develop into clitoris, labia, outer vagina

If hormones don’t occur:
- Wolffian system, without androgens, withers away

Question 4

What are the factors controlling development of the male sex organs?

Answer 4

• Male = XY to (testis-determing factor) = primordial gonads develop into testes

If masculinisation and androgens occur:
EITHER:
- Wolffian system develops into vas deferenes, seminal vesicles, prostate
- Primordial external genitalia develop into penis and scrotum

If defeminisation and anti-müllerian hormone occur:
- Müllerian systems withers away

Question 5

What is the Testes determining factor that controls the development of male sex organs?

Answer 5

• 230 amino acid long protein coded by SRY region of Y chromosome
• (sex determining region of the Y chromosome)
• point mutations can prevent development of testes (and hence of internal and external male sex organs) in XY individuals
• chromosomally male but appear female
• usually infertile (not always though)