Sex Determination

Question 1

The embryo decides whether to be male or female when

Answer 1

Making gonads

Question 2

Germ line cells come from

Answer 2

The epiblast - found at the top of the yolk sac

Were not included in gastrulation

Question 3

Primordial germ line cells

Answer 3

Use the gut to move along to the gonadal ridge in order to invade the body
Then move up the mesentery and then move across to enter the gonads themselves

Question 4

SRY

Answer 4

Male determining gene

Question 5

Primitive gonads consist of

Answer 5

Somatic cells and germ line cells

Question 6

Somatic cells in the gonad

Answer 6

Express SRY if it is present

Question 7

The expression of SRY initiates

Answer 7

A cascade of genes to force somatic cells to develop testes

Question 8

If SRY is not expressed

Answer 8

Ovaries develop

Question 9

Testes communicate with the rest of the body via

Answer 9

Excreting androgen is hormones

Question 10

Complete androgen insensitivity

Answer 10

Testosterone receptors inactive -> result that somatic cells cannot recognise testosterone

Has XY and therefore male gonads but appears female

Has lower vagina but no uterus, cervix, upper vagina, oviducts - do not menstruate

Question 11

XY children with deficient 5alpha-reductase

Answer 11

Make female bodies until puberty when testosterone levels rise begin to develop male phenotype

Question 12

Testosterone

Answer 12

Is a relatively weak androgen

Question 13

5 alpha-reductase

Answer 13

Enzyme which converts testosterone into 5 alpha dihydrotestosterone

Question 14

5 alpha dihydrotestosterone

Answer 14

Stimulates androgen receptors strongly

Stronger version of testosterone