Reproductive: Steroidogenesis, Folliculogenesis, ovulation

Question 1

Where does LH bind?

Answer 1

theca cells

granulosa cells only during luteal phase

Question 2

What is the action of LH on theca cells?

Answer 2

produce androstenedione or testosterone which enter the granulosa cells for conversion into estradiol

Question 3

What is the action of LH during the luteal phase?

Answer 3

binds on granulosa cell to produce progesterone that feeds back into the theca cell for more conversion to androgen

Question 4

LH is necessary to produce progesterone during the luteal phase. Why is this important?

Answer 4

progesterone is required to maintain pregnancy if fertilization/implantation occurs

Question 5

Where does FSH bind?

Answer 5

granulosa cells only

Question 6

What is the action of binding of FSH on granulosa cells?

Answer 6

aromatization of androgens to estradiol;

produce more LH receptors on granulosa cells

Question 7

What is the importance of estradiol?

Answer 7

released into blood to act locally (increase FSH sensitivity);
systemically to inhibit GnRH secretion

Question 8

What produces the molecule for negative feedback in female steroidogenesis?

Answer 8

Granulosa cells produce inhibin to inhibit further FSH secretion

Question 9

When does estradiol not work as a negative feedback inhibitor?

Answer 9

during ovulatory period

Question 10

Define primordial follicle

Answer 10

immature follicle surrounded by pregranulosa cells ARRESTED IN PROPHASE I OF MEIOSIS until maturation

Question 11

When does a primordial follicle become a primary follicle?

Answer 11

at puberty during each menstrual cycle

Question 12

What defines a primary follicle?

Answer 12

oocyte enlarges and granulosa cells mature and proliferate

Question 13

Granulosa cells aid the primary follicle how?

Answer 13

secrete mucopolysaccharides creating ZONA PELLUCIDA to protect the oocyte and provide nutrients and chemicals for growth

Question 14

As primary follicle matures, what is added to proceed to a secondary follicle?

Answer 14

granulosa cell layers are added and layer of androgen producing theca cells => THECA INTERNA surround follicle

Question 15

After the Theca interna is present around the secondary follicle, what occurs?

Answer 15

continues to grow and fibrous theca externa surrounds follicle

Question 16

Define antrum

Answer 16

follicular cavity that forms from granulosa cell secretions after the fibrous theca externa surrounds follicle

Question 17

What type of follicle is ready for ovulation?

Answer 17

Graafian follicle (mature)

Question 18

When does the Graafian follicle resume meiosis? what occurs next?

Answer 18

LH surge to complete 1st Meiotic division => arrested in metaphase of Meiosis 2 prior to ovulation

Question 19

What is the result of meiosis on the follicle?

Answer 19

produces nonfunctional 1st polar body (degenerates) and larger 2ndary haploid oocyte

Question 20

What happens if 2ndary haploid oocyte is fertilized?

Answer 20

completes Meiosis 2 to form MATURE OOCYTE and POLAR BODY

Question 21

What is the first step in ovulation?

Answer 21

antral fluid increases pressure until follicle ruptures and oocyte is extruded

Question 22

After ovulation, what is the job of the theca and granulosa cells?

Answer 22

theca secretes estrogen;

granulosa secretes progesterone

Question 23

What is the result of theca and granulosa secretions after ovulation?

Answer 23

produce corpus luteum => new endocrine organ that grows until day 7 after ovulation

Question 24

If fertilization occurs to corpus luteum, how does it grow?

Answer 24

grows for 3 months via hCG maintenance from embryo until placenta is functional