Sexual Development
Development of Sex Organs
•
Gonads
–
Testes
–
Ovaries
•
Internal genitalia
•
External genitalia
Gonads
Develops first
Produce ova or
sperm
Undifferentiated
until after about
6 weeks
SRY Gene
•
Sex-determining Region Y
•
Gene on the Y chromosome
•
Produces a protein that binds to the DNA of
cells in undifferentiated gonads and causes
them to become testes (testicles)
•
If it is not present, the gonads become ovaries
Hormonal Effects
•
Organizational effects
–
Influence the development of a person’s sex organs
and brain
–
Permanent (once initiated, there is no going back)
•
Activational effect
–
Effects occur later in life, after sex organs have
been developed
–
(i.e., induce ovulation)
•
Hormones determine gender
Müllerian System
•
Default system
•
Does not need
hormonal stimulus
from the gonads
Wolffian System
•
Needs hormones from
the testes
•
Anti-Müllerian
hormone
•
Defeminizing
effect
•
Androgens
•
Steroid hormones
that stimulate
development of
the Wolffian
system
•
Masculinizing
effect
