Chapter 8.3 Sexual Differentiation

Question 1

What is Sexual differentiation?

Answer 1

Early process in which a fetus begins to develop a male (XY) or female (XX) body and behaviors

Question 2

How to know whether a baby will be a male or female.

Answer 2

If sperm has an X chromosome it will become female, if it has a Y chromosome it will become male

Question 3

What is the SRY gene?

Answer 3

It’s the sex determining region on the Y chromosome. Responsible for the development of testes; without it ovaries would form

Question 4

What is a genital tubercle?

Answer 4

A bump between the legs of an early fetus that can form either a clitoris or a penis

Question 5

Where does the mullein ducts form in females?

Answer 5

In the fallopian tubes, the uterus, and vagina (wolffian ducts shrink at 8 weeks)

Question 6

Where does the Wolffian ducts in male form?

Answer 6

In the epididymis, vas deferens, and seminal vesicles (mullein ducts shrink)

Question 7

What two hormones from the testes masculinize the system

Answer 7

Testosterone and Anti-mullerian hormone

Question 8

How does Testosterone masculinize the system?

Answer 8

It promotes the development of the wolffian system

Question 9

How does the Anti-Mullerian masculinize the system?

Answer 9

It induces the regression of the mullerian system

Question 10

What other structures does testosterone masculinize?

Answer 10

The scrotum and the Penis

Question 11

What is the 5-alpha-reductase?

Answer 11

It is enzyme that converts testosterone into a more powerful androgen known as Dihydrotestosterone; required for male genitalia masculinization

Question 12

What is the Turner’s Syndrome

Answer 12

When a person has only one sex chromosome- a single X

Question 13

Turner’s syndrome

Answer 13

The individual develops as a female but since there are no SRY gene they don’t have any masculinizing effect

Question 14

What is Congenital adrenal hyperplasia (CAH)?

Answer 14

It where developing females are exposed to excess androgens before birth; new borns have normal ovaries; no testes; and may have intersex appearances

Question 15

What is intersex?

Answer 15

It is when genitalia are intermediate in form between typical male and typical female genitalia

Question 16

What is Androgen insensitivity syndrome?

Answer 16

Occurs when an XY fetus has a defective gene for the androgen receptor; embryo tissue doesn’t respond to circulating testosterone, testes remain internal but external tissue develop as female, can form breasts but are infertile(neither ovaries or uterus present)

Question 17

What is the 5 alpha-reductase deficiency?

Answer 17

When XY(male) lacks the gene responsible for the enzyme converting testosterone to DHT; fetus develop normal male internal reproductive structure but external structure fail to masculinize; at puberty more male development kicks in and increase production of androgens and penis size

Question 18

What is the organizational effect?

Answer 18

The same steroids that masculinize the developing genitalia also masculinize the brain; permanently alters the brain and behavior

Question 19

When are hormones effective?

Answer 19

When present during a sensitive period in early development; before or after birth; can also be during puberty

Question 20

What is sexual dimorphism?

Answer 20

Marked differences in appearance between males and females, also apparent in the brain

Question 21

What is responsible for sexual dimorphism in the brain?

Answer 21

Androgens

Question 22

How does sexual dimorphism appear in rats?

Answer 22

The sexual dimorphic nucleus of the POA in the hypothalamus is 5-6 times larger in males than in females; lesions there disrupts ovulatory and copultatory behavior

Question 23

What is Bulbocavernosus (BC)?

Answer 23

Muscles that surround the base of the penis and inner aged by neurons in the spinal nucleus of the Bulbocavernosus (SNB)

Question 24

SNB larger in males than in females

Question 25

Before birth, the BC in both sexes are nearly equivalent, after birth both SNB and BC muscles die in females; injection of androgen can prevent this

Question 26

What are two possible influences on gender identity and sexual orientation?

Answer 26

Biology and socialization

Question 27

Homosexual behavior occurs in other species

Question 28

The INAH-3 nucleus of the POA is larger in men and in heterosexual men

Answer 28

Unclear if size difference is a result of homosexuality

Question 29

What is the fetal androgen exposure makers in women?

Answer 29

Lesbians were exposed to more fetal androgen than heterosexuals (finger length patterns (2D to 4D)

Question 30

What is the Fraternal birth order effect?

Answer 30

A boy with a higher number of biological brother and being right handed can cause boys to be gay