Sex Determination and Differentiation

Question 1

biological sex, the physical body

Answer 1

sex

• essentially the “biological and physiological characteristics that distinguish females from males”

Question 2

self identification of being intrinsically male, female or alternative gender

Answer 2

gender

• this includes “socially constructed roles, relationships, behaviors, relative power and other traits societies ascribe to women and men”

Question 3

is the early developmental event that dictates whether a fetus will be male or female

• chromosome driven

Answer 3

sexual determination

Question 4

early process in which a fetus begins to develop a male or female body and behaviors

• hormone driven

Answer 4

sexual differentiation

Question 5

if the sperm that enters the egg has a Y chromosome, the offspring will become male

• SRY gene (sex determining region on the Y chromosome) is responsible for the development of testes)

Answer 5

how is sex determined?

Question 6

if the sperm carries an X chromosome, the offspring will become female, without the SRY gene:

Answer 6

ovaries form

Question 7

the … develop into the internal male reproductive structures (epidiymis, vas deferens and seminal vesicles) and the Mullein ducts regress, which is driven by testosterone from the testes

Answer 7

Wolffian ducts

Question 8

the … (which develops into the female reproductive structures of Fallopian tubes, uterus and vagina) shrinks because of the anti-mullerian hormone (AMH) from the testes

Answer 8

Mullerian ducts

Question 9

testosterone can be converted to 2 other hormones: … (an enzyme) converts T into dihydrotestosterone (DHT); required for external male genitalia masculinization

• … converts T in estradiol (E) responsible for masculinizing the brain

Answer 9

5a-reductase and aromatase

Question 10

in … a person only has one sex chromosome – a single X

• a feminine body develops due to lack of the SRY gene, with abnormal ovaries (no steroid hormone production or eggs)
• estrogen treatment at puberty induces breast growth and a female-typical puberty

Answer 10

Turners Syndrome

Question 11

androgen insensitivity syndrome (AIS) occurs in XY individuals with defective androgen receptors (so, androgens cannot have action)

• testes because of the SRY gene on the Y chromosome
• T (and also DHT), AMH
• Female

Answer 11

will they develop testes or ovaries?

what hormones will be produced? which will act?

what will be the phenotype of the individual?

Question 12

pronounced differences in appearance between male and females

• reproductive structures
• differences in the brain
• size, connectivity, number of neurons, neural density, etc
• These differences are due to early exposure to hormones

Answer 12

sexual dimorphism

Question 13

• occurs before the brain matures
• critical/sensitive period
• permanent effects
• structural changes in the brain

Answer 13

organizational effects of hormones

Question 14

in adulthood is affect by organizational hormones AND the circulating hormones in aduthood that act upon (or activate) the circuitry that was organized during the critical period

Answer 14

behavior

Question 15

• occurs in adulthood
• no sensitive period
• transitory (short-acting)
• biochemical changes

Answer 15

activational effects of hormones

Question 16

yes!!

the deciding factor for what kind of effect the hormone will have is:

Answer 16

can the same hormone be both organizational AND activational?

the timing of its action (steroid hormones have an organizational effect only when present during the critical period of development)

Question 17

depending on the species and the behavior, this period may be before birth or just afterwards, in the … period

Answer 17

neonatal

Question 18

two possible influences on gender identity and sexual orientation

Answer 18

• socialization
• biology

Question 19

the more older brothers a boy has, the more likely he is to grow up to be gay

• this is only true for biological brothers sharing the same mother
• the effect looks like it may be driven by the mother’s immune system with subsequent pregnancies

Answer 19

fraternal birth order effect

Question 20

IMPORTANTLY: a persons identity and orientation are influenced by a variety of factors:

Answer 20

biology is only one of those factors