Chapter 22

Question 1

The gonads have the dual function of…

Answer 1

Gametogenesis and secretion of sex hormones

Question 2

_____ are steroid hormones that are masculinizing in their action

Answer 2

Androgens

Question 3

_____ are steroid hormones that are feminizing in their action

Answer 3

Estrogens

Question 4

This steroid hormone has special functions in preparing the uterus for pregnancy

Answer 4

Progesterone

Question 5

This polypeptide hormone is released to loosen the ligaments of pubic symphysis and soften the cervix

Answer 5

Relaxin

Question 6

This polypeptide inhibits FSH secretion

Answer 6

Inhibin B

Question 7

These anterior pituitary gonadotropins aid in the secretory and gametogenic functions of the gonads

Answer 7

FSH and LH

Question 8

What is the difference in gonadotropin secretion between males and females?

Answer 8

In males secretion is non-cyclic, in females secretion is periodic and necessary for menstruation, pregnancy, and lactation.

Question 9

This locus on the Y chromosome contains the testis-determining gene product

Answer 9

SRY (sex-determining region of the Y chromosome)

Question 10

Which drug arrests mitosis at the metaphase?

Answer 10

Colchicine

Question 11

What region of the X chromosome in females turns off one of the other X chromosomes?

Answer 11

X-inactivation center (probably via CTCF)

Question 12

What structure does the inactive X chromosome form in female cells?

Answer 12

Barr body (usually near the nuclear membrane)

Question 13

What embryological structure does the gonad develop from?

Answer 13

A genital ridge of tissue near the adrenal gland.

Question 14

How long is the genital ridge identical between the two sexes?

Answer 14

Six weeks of development

Question 15

What happens to the genital ridge in males between the seventh and eighth week of development? What cell types appear? What hormones are released?

Answer 15

The medulla develops into the testis, and the cortex regresses. Leydig and Sertoli cells appear and testosterone and MIS are secreted.

Question 16

What happens to the genital ridge in females between the seventh and eighth week of development? What hormones are released?

Answer 16

The cortex develops into an ovary, and the medulla regresses. The embryonic ovary does not release any hormones.

Question 17

What duct system develops in an embryo destined to be a female? What about a male?

Answer 17

For females, the mullerian duct system develops into uterine tubes (oviducts) and a uterus.
For males, the wolffian duct system develops into the epididymis and vas deferens.

Question 18

What happens to the urogenital slit in embryos destined to become female? Male?

Answer 18

In males, the urogenital slit disappears; for females, the urogenital slit remains open.

Question 19

What are the effects of androgen exposure to an embryo?

Answer 19

In rats, monkeys, and humans masculinizing effects on behavior appear. However, in humans and monkey, cyclical gonadotropin secretion still occurs.

Question 20

What is nondisjunction? When is it most likely to occur?

Answer 20

Nondisjunction is when a pair of chromosomes fail to separate during a meiotic division. This typically occurs in meiosis I, but can occur in meisois II.

Question 21

What chromosomal patterns underlie Turner syndrome? Klinefelter syndrome? “Superfemales”? And one more that is lethal in utero?

Answer 21

Turner: XO; Klinefelter: XXY; “Superfemales”: XXX; YO combination is lethal in utero.

Question 22

How are chromosomal abnormalities diagnosed?

Answer 22

Amniocentesis: sample of amniotic fluid collected by inserting a needle through the abdominal wall.

Chorionic villus sampling: fetal cells collected by a needle biopsy.

Question 23

How does female pseudohermaphroditism occur? What external genitalia are present? What gonadal sex is present?

Answer 23

Exposure of a genetic female to androgens during week 8-13 of development. External male genitalia if exposed early, clitoral hypertrophy if exposed after the 13th week; gonadal sex is female.

Question 24

What is a pseudohermaphrodite?

Answer 24

An individual with the genetic constitution and gonads of one sex and the genitalia of the other.

Question 25

What is one cause of female pseudohermaphroditism?

Answer 25

Congenital virilizing adrenal hyperplasia has a lack of androgen formation (deficiency in cholesterol desmolase) leading to formation of female genitalia despite genetic sex.