Development of the Reproductive Tract

Question 1

When is chromosomal sex determined?

Answer 1

At time of fertilization
Oocyte (x) + sperm (x) or sperm (y)
xx = female, xy = male

Question 2

What determines gonadal sex?

Answer 2

Presence of Y chromosome
Sry (sox9) = male internal + external characteristics

Question 3

What is the importance of the SRY gene?

Answer 3

SRY (+) = Male (testes)
SRY (-) = Female (ovaries)

Question 4

What is the significance of an XXY genotype?

Answer 4

Testes = SRY present on Y chromosome

Question 5

What is the significance of an XO genotype?

Answer 5

Ovaries = no SRY present because no Y chromosome

Question 6

What are the supporting cells of the testes? What is their function?

Answer 6

Sertoli cells
Sperm development

Question 7

What are the cells composing the tissues between sex cords? What is their function?

Answer 7

Leydig cells
Make testosterone

Question 8

What are the supporting cells of the ovary?

Answer 8

Granulosa cells

Question 9

What are the interstitial cells of the ovary? What is their function?

Answer 9

Theca cells
Make estradiol from testosterone

Question 10

Diagram the process of male gonadal differentiation

Answer 10

Tubular

Question 11

Diagram the process of female gonadal differentiation

Answer 11

Follicular

Question 12

What cells are analogous in male and female gonadal differentiation?

Answer 12

Sex cords give rise to sertoli cells (M) and granulosa cells (F)
Mesenchyme gives rise to leydig cells (M) and theca cells (F)

Question 13

Which duct is the precursor to male internal genitalia?

Answer 13

Wolffian duct

Question 14

Which duct is the precursor to female internal genitalia?

Answer 14

Mullerian duct

Question 15

What 2 hormones play a role in male and female internal genitalia development? What role do they play? What cells make them?

Answer 15

Testosterone (leydig cells)= promotes development of Wolffian (M) duct
Anti-Mullerian Hormone (sertoli cells) = regression of Mullerian (F) duct

Question 16

How does the male internal genitalia tract develop?

Answer 16

Sertoli cells produce AMH = regression of Mullerian (F) duct
Leydig cells produce testosterone = stimulation of Wolffian (M) duct

Question 17

How does the female internal genitalia tract develop?

Answer 17

No AMH = allows development of Mullerian (F) ducts
No (high levels) or testosterone = regression of Wolffian (M) ducts

Question 18

How does the male external genitalia develop?

Answer 18

Testosterone is converted to Dihydrotestosterone (DHT) via the enzyme 5-A-Reductase
DHT directs formation of the penis and scrotum

Question 19

What external genitalia develops in the absence of dihydrotestosterone?

Answer 19

Female
(Also occurs if there are no receptors for DHT)

Question 20

Define: Hermaphrodite

Answer 20

Both ovarian and testicular tissue is present
(Rare, most common in swine)

Question 21

Define: Pseudohermaphrodite

Answer 21

Gonads of one sex and accessory reproductive organs of the opposite sex

Question 22

Compare: Male v Female Pseudohermaphrodite

Answer 22

Male = testes + female external genitalia
Female = ovaries + male external genitalia

Question 23

What are the 2 mechanisms in which androgen resistance can occur? What does an individual with this syndrome look like?

Answer 23

XY with bilateral testes, normal Mullerian duct regression, normal secretion of testosterone but female external genitalia
Due to 5A reductase deficiency (can’t convert testosterone to DHT)
Due to androgen receptor dysfunction (testosterone cannot induce development of Wolffian ducts and DHT cannot stimulate masculinization of external genitalia)

Question 24

Define: Drug-Induced Intersex

Answer 24

Exposure of female fetuses to androgens in utero may lead to masculinization of female fetus

Question 25

Define: Adrenogenital Syndrome

Answer 25

Enzyme deficiency in adrenal gland leads to overproduction of androgens and masculinization of female fetus

Question 26

Define: Persistent Mullerian Duct Syndrome

Answer 26

Inherited disorder of AMH production
Oviducts, uterus, cervix, and cranial vagina present

Question 27

Define: XX Sex Reversal

Answer 27

Testes or ovotestes present in XX female

Question 28

Define: Freemartinism

Answer 28

Intersex female born co-twin to a male
Occurs as a result of early fusion of placental blood vessels between twins, allowing interchange of blood
Androgens and AMH from male twin

Question 29

Define: Cryptorchidism

Answer 29

Failure of testes to descend completely into the scrotum
Azoospermia, male behavior, increased risk of testicular tumors