Jackson Lectures 5

Question 1

Enzymes that convert T to other steroids can be manipulated for

Answer 1

therapeutic reasons

Question 2

aromatase inhibitors used to treat

Answer 2

breast and prostate cancers

Question 3

5α-reductase inhibitors used to treat

Answer 3

hair loss. DHT promotes hair loss in male pattern baldness.

Question 4

Andropause is considered the male counterpart to

Answer 4

menopause, although andropause is far less dramatic because there are no clear physiological changes

Question 5

andropause is characterized by an increase in

Answer 5

emotional disorders associated with aging

Question 6

no obvious decline in reproductive function during andropause although testosterone production does decrease with age
most men remain fertile despite

Answer 6

decreased sperm counts and motility

not clear if T decline is associated with emotional problems

Question 7

1. oocytes – each oocyte is enclosed within a sphere of cells called an

Answer 7

ovarian follicle. Note that there are no oogonia.

Question 8

Shortly after birth, all oocytes are arrested in

Answer 8

prophase of meiosis I.

Question 9

ovarian function is cyclical and typically, one mature ovum is released per

Answer 9

cycle. So although there are more than enough oocytes for the number of ovarian cycles in a female’s lifetime, the total number is limited.

Question 10

2. Theca cells surround each

Answer 10

follicle; location and function is analogous to that of Leydig cells.

Question 11

3. Granulosa cells are the

Answer 11

epithelial cells of the follicle (analogous to Sertoli cells).

Question 12

In an early follicle, one or more layers of cells surround the oocyte. Large, developing follicles become filled with

Answer 12

fluid, and some granulosa cells continue to surround the oocyte in the cumulus oophorus.

Question 13

4. Luteal cells are present after

Answer 13

ovulation when the theca and granulosa cells from the ovulatory follicle are transformed into the cells of the corpus luteum.

Question 14

The two cell – two gonadotropin model applies to the endocrine function of the

Answer 14

ovary, similar to what was discussed for testicular endocrinology.

Question 15

Theca cells synthesize

Answer 15

androstenedione in response to LH

Question 16

androstenedione diffuses into

Answer 16

granulosa cells

Question 17

some androgen diffuses into the

Answer 17

systemic circulation

Question 18

In response to FSH, granulosa cells

convert androstenedione to

Answer 18

estrone which is converted to estradiol (E2)

Question 19

estradiol stimulates

Answer 19

granulosa cell function and replication

Question 20

granulosa cells regulates

Answer 20

oocyte development

regulates female secondary sex characteristics

Question 21

granulosa cells important regulator of

Answer 21

bone turnover and arterial function

Question 22

granulosa cells typically inhibits

Answer 22

GnRH and LH secretion

Question 23

granulosa cells secrete

Answer 23

inhibin that has a negative feedback effect on FSH secretion

Question 24

Note that larger follicles are going to have more

Answer 24

LH and FSH receptors, and will produce greater amounts of both E2 and inhibin. These are important factors regulating an ovarian cycle.

Question 25

Ovarian cycle

Answer 25

1 and 2: gonadotropin rise and follicular development

3-5: increase E2 and inhibin; dominant follicle selection

6-8: FSH decrease, E2 peak, LH surge (positive feedback action of E2 on GnRH and LH)

9-11: meiosis I completed, ovulation, CL formation

12-13: increase E2 and P, inhibit gonadotropins

14-16: CL regression, decrease steroids, gonadotropins rise

Question 26

Menstrual or uterine cycle follows or parallels the

Answer 26

ovarian cycle

Question 27

menstrual phase: begins when the

Answer 27

CL regresses and steroid support for uterine endometrium is lost

Question 28

proliferative phase: follicular E2 stimulates proliferation of the

Answer 28

endometrium

Question 29

follicular phase ends with

Answer 29

ovulation and CL formation

Question 30

luteal phase: P and E2 stimulate

Answer 30

uterine secretory activity; increase glandular production of glycogen, increase angiogenesis, decrease contractility

Question 31

CL regresses (gonadotropins too low) and cycle

Answer 31

begins again

Question 32

If pregnancy occurs, the placenta produces

Answer 32

human chorionic gonadotropin (hCG) which is similar to LH and maintains luteal steroidogenesis until the placenta develops fully.

Question 33

human chorionic gonadotropin (hCG) which is similar to

Answer 33

LH and maintains luteal steroidogenesis until the placenta develops fully.

Question 34

Menopause – cessation of menstrual cycles primarily

Answer 34

due to ovarian failure

Question 35

menopause loss of ovarian follicles due to

Answer 35

atresia

Question 36

hormonal consequences of menopause

Answer 36

lose ovarian steroids

gonadotropin and inhibin secretion very high

increase reliance on adrenal steroids

Question 37

The fetal testis produces two hormones that regulate

Answer 37

sexual differentiation of the internal genitalia – T and Müllerian inhibiting substance (MIS)

Question 38

In the undifferentiated state, there are two sets of tubules associated with the developing gonad –

Answer 38

the Wolffian ducts and the Müllerian ducts

Question 39

IN males; T stimulates proliferation of the

Answer 39

Wolffian duct system that will become the tubules associated with the male reproductive tract.

Question 40

MIS causes the Müllerian duct system to .

Answer 40

regress

Question 41

In a developing female:

Absence of T causes

Answer 41

regression of the Wolffian duct system

Question 42

Absence of MIS results in

Answer 42

proliferation or maintenance of the Müllerian duct system that becomes the tubules of the female reproductive tract.

Question 43

Differentiation of the external genitalia

The early embryo and fetus are undifferentiated up to

Answer 43

~9 weeks of gestation. Both the male and female external genitalia include a genital tubercle, urogenital fold, and labioscrotal fold/genital folding.

Question 44

Androgens from the developing testes (mostly T converted peripherally to DHT) stimulate

Answer 44

differentiation of male external genitalia

Question 45

genital tubercle →

Answer 45

glans of penis

Question 46

urogenital fold →>

Answer 46

urethra and surrounding penis

Question 47

labioscrotal folds →

Answer 47

scrotum and skin of penis

Question 48

In the absence of androgens in the female

genital tubercle →

Answer 48

glans of clitoris

Question 49

absence of androgens in female:

urogenital fold →

Answer 49

labia minor and urethral opening

labioscrotal fold → labia majora

Question 50

absence of androgens in female:

labioscrotal fold →

Answer 50

labia majora

Question 51

The brain is also sexually differentiated due to the effects of

Answer 51

T aromatized to E2 in the developing male.