3 - RECEPTOR/ENZYME DEVELOPMENTAL DISORDERS

Question 1

androgen insensitivity disorder

Answer 1

• XY males with non-functioning androgen receptors
• don’t respond to androgens so go down default path (intrinsic female path)
• still possess testes with functioning sertoli and leydig cells
• normal hormone production (MIH and androgen)
• development of internal female reproductive system repressed - so no uterus or ovaries (no menstruation)
• MIH regresses müllerian duct - wolffian also regresses due to no androgen receptors
• external phenotype = female (depending on amount of receptors)

Question 2

5alpha-reductase deficiency syndrome

Answer 2

• XY males without 5a-reductase (enzyme)
• testosterone not converted to DHT
• female (or intersex if some 5a-reductase) external genitals
• increased testosterone production in puberty
• may cause development of male genitals
• external phenotype = female at birth -> male at puberty

Question 3

androgen insensitivity disorder in RATS

Answer 3

• XX females will produce female typical sexual behaviour
• female-typical sexual behaviour requires estrogen and progesterone in rats (so XY males with the disorder will still not produce female typical sexual behaviour)
• neither sexes will produce male-typical sexual behaviour as androgens needed (or receptors for them)
• XY males will produce no sexual behaviour

Question 4

androgen insensitivity disorder

internal reproductive organs

(3 facts)

Answer 4

still possess testes with functioning sertoli and leydig cells

development of internal female reproductive system repressed - so no uterus or ovaries (no menstruation)

MIH regresses müllerian duct - wolffian also regresses due to no androgen receptors

Question 5

androgen insensitivity disorder

external phenotype

Answer 5

female (depending on amount of receptors

Question 6

androgen insensitivity disorder

hormone production

Answer 6

normal hormone production (MIH and androgen)

XY males