Lecture 2a – biology of sexuality
1) Chromosomal sex
2) Gonadal sex
3) Hormonal sex
4) Morphological sex
5) Behavioral sex
1) chromosomal sex: 23rd pair determine XX (female) or XY (male), female or male anatomy
similarities and differences
2) gonadal sex: we start with bipotential gonads will develop either ovaries or testes (or both but
that is very rare) at 6 weeks of gestation, gonads are the same. The wolffian ducts will develop into
penis (testicular and epididymis, sperm production), müllerian ducts will develop into uterus and
fallopian tubes. The genital fold develops into …, genital tubercle into … .
At 15 weeks testes are developed and fallopian tubes, glans/clitoris, labia, minora/scrotal swelling,
vagina/penis come from the same tissue, but due to hormones they develop either male or
female.
3) hormonal sex: Phoenix, 1959: organization hypothesis in utero steroid hormones affect the
structure of the brain and body develop penis/vulva, brain structures. But in the infant brain there is
so much overlap that there are no visual differences. It sets the body up for puberty, activational
effects puberty-steroid hormones affect morphology and activate psychological effects.
Vulva:
vagina is only the internal structures, vulva is the name of the whole: both inside and outside. The
clitoris is mostly inside, same tissue as the penis glans clitoris is outside knob, g-spot is on the
behind-side of the clitoris.
The vaginal corona (aka hymen): similar as the penis shaft and top. The hymen can stretch or tear
(due to horsebackriding or use of tampons, it doesn’t “break” with losing virginity). There are four
types: normal, imperforate, micro perforate, septal hymen
Penis:
penile shaft with two tubes (urine and sperm, there is a sphincter so the two don’t intertwine)
Intersex genitalia:
various hormonal and genetic factors can contribute to genitalia that are between a penis and vagina
or incomplete structures:
- hypospadia
- congenital adrenal hyperplasia
- 5-alpha-reductase deficiency (guevedoces in Dominican Republic, not DHT, female at birth but when
puberty hits around 12, the testosterone kicks in and male genitals develop, that’s why the name is
dick at twelve)
- turner syndrome (XO): chromosomal, only X chromosome. There is nothing to support wolffian or
inhibit mullerian ducts.
Role of hormones:
- have the physiological and psychosocial effects
- only increase the likelihood of behaviour occurring hormones do not control us!
- there is a reciprocal relationship between hormones, behaviour and environment (social/world)
1) Chromosomal sex
2) Gonadal sex
3) Hormonal sex
4) Morphological sex
5) Behavioral sex
1) chromosomal sex: 23rd pair determine XX (female) or XY (male), female or male anatomy
similarities and differences
2) gonadal sex: we start with bipotential gonads will develop either ovaries or testes (or both but
that is very rare) at 6 weeks of gestation, gonads are the same. The wolffian ducts will develop into
penis (testicular and epididymis, sperm production), müllerian ducts will develop into uterus and
fallopian tubes. The genital fold develops into …, genital tubercle into … .
At 15 weeks testes are developed and fallopian tubes, glans/clitoris, labia, minora/scrotal swelling,
vagina/penis come from the same tissue, but due to hormones they develop either male or
female.
3) hormonal sex: Phoenix, 1959: organization hypothesis in utero steroid hormones affect the
structure of the brain and body develop penis/vulva, brain structures. But in the infant brain there is
so much overlap that there are no visual differences. It sets the body up for puberty, activational
effects puberty-steroid hormones affect morphology and activate psychological effects.
Vulva:
vagina is only the internal structures, vulva is the name of the whole: both inside and outside. The
clitoris is mostly inside, same tissue as the penis glans clitoris is outside knob, g-spot is on the
behind-side of the clitoris.
The vaginal corona (aka hymen): similar as the penis shaft and top. The hymen can stretch or tear
(due to horsebackriding or use of tampons, it doesn’t “break” with losing virginity). There are four
types: normal, imperforate, micro perforate, septal hymen
Penis:
penile shaft with two tubes (urine and sperm, there is a sphincter so the two don’t intertwine)
Intersex genitalia:
various hormonal and genetic factors can contribute to genitalia that are between a penis and vagina
or incomplete structures:
- hypospadia
- congenital adrenal hyperplasia
- 5-alpha-reductase deficiency (guevedoces in Dominican Republic, not DHT, female at birth but when
puberty hits around 12, the testosterone kicks in and male genitals develop, that’s why the name is
dick at twelve)
- turner syndrome (XO): chromosomal, only X chromosome. There is nothing to support wolffian or
inhibit mullerian ducts.
Role of hormones:
- have the physiological and psychosocial effects
- only increase the likelihood of behaviour occurring hormones do not control us!
- there is a reciprocal relationship between hormones, behaviour and environment (social/world)
