Development Of The Ovarian Follice

Question 1

What is the function Granulosa cells in regards to a primary oocyte?

Answer 1

1) They remain attached to the oocyte throughout development
2) They provide nutrients to the oocyte

Question 2

The first primary oocyte appears ____ and generation of primary oocytes is usually complete by when?

Answer 2

1) Six weeks into intrauterine life

2) Complete by: ~6 months of birth

Question 3

What is the function of AMH (Anti-Mullerian Hormone)?

Answer 3

It prevents the over production of primordial follicles

Question 4

Primary oocytes usually progress through which stage and become arrested at what stage?

Answer 4

1) Progress: Prophase I

2) Arrest: Diplotene stage

Question 5

What is the very first form of a primary oocyte?

Answer 5

Resting Primordial Follicle

Question 6

When is a follicle considered to be a primary follicle?

Answer 6

Appearance of cuboidal granulosa cells

Question 7

What defines a secondary follicle?

Answer 7

Primary oocyte surrounded by several layers of cuboidal granulosa cellls

Question 8

What constitutues the formation of a Mature Preantral Follice?

Answer 8

1) Follicle aquires 3-6 layers of cuboidal granulosa cells
2) Secretes paracrine factors onto nearby stromal cells –> differentiate into epitheloid thecal cells
3) Thecal cell layer forms

Question 9

What is included in the progression to a secondary follice?

Answer 9

1) Follice moves from the cortex into the medulla (greater access to vascular supply)
2) Follice also release angiogenic factors that produce 1-2 arterioles that wrap the follilce in a vascular sheath

Question 10

What is reponsible for the formatoin of the Zona Pellucida?

Answer 10

Production of extracellular matrix glycoproteins {ZP1, ZP2, & ZP3} via the preantral follicle

Produced when the primary oocyte in the preantral follicle fails to undergo complete process of Meiosis

Question 11

In regards to a growing Preantral Follicle:

What is the endocrine function of Granulosa Cells?

Answer 11

1) THey contain receptors for FSH but rely on the Primary oocyte for growth
2) No ovarian steroid hormones are being produced at this stage

Question 12

In regards to a growing Preantral Follicle:

1) What is the endocrine function of Thecal Cells

P.s- What are Thecal cells derived from?

Answer 12

1) Thecal Cells: Analogous to Leydig Cells –> Producing Androstenedione

1B) They lack 17B-hydroxysteroid dehydrogenase (can’t convert androstenedione into testosterone)

2) Derived from Stromal Cells

Question 13

Is Androstenedione production, present or absent, in the Thecal cells of a growing preantral follice?

Answer 13

Absent to minimal production

Question 14

During the growth of an antral follice; there is the division of the granulosa cells into two populations. What are they?

Answer 14

1) Mural Granulosa Cells (Stratum Granulosum)- Outer

2) Cumulus Cells (Cumulus Oophorus or Corona Radiata) - Inner

Question 15

What happens to the mural granulosa cells after ovulation?

Answer 15

They remain in the ovary to become the corpus luteum

Question 16

What occurs to the cumulus cells (Zona Radiata) during ovulation?

Answer 16

They are released from the ovary along with the oocyte (cumulus-oocyte complex)

Question 17

In the antral stage, oocytes gain the competence to undergo the completion of meiosis but are still arrested in the cycle.

1) What accounts for the gain of competence to complete meiosis?
2) What accounts for the maintenance of cell cycle arrest?

Answer 17

1) Competence: Oocytes synthesize sufficient amounts of Cyclin dependent kinase & Cyclin B
2) Arrest: Via high levels of cAMP

Question 18

In regards to growing Antral Follicles:

What is the endocrine function of Thecal cells?

Answer 18

THecal Cells: They produce androstenedione (primarily) & small amounts of Testosterone (T)

Question 19

In regards to the growing Antral Cells:

What is the endocrine function of the Granulosa Cells?

Answer 19

1) They have FSH receptors, which stimulate their proliferation
2) Stimulation via FSH also induces the expression of CYP19-aromatase

Question 20

In regards to the Growing Antral Follicles:

What converts androgesn into Estradiol-17B?

Answer 20

Mural Granulosa Cells (Outer)

Question 21

What is the endocrine function in regards to the Granulosa Cells in a Dominant Follicle?

Answer 21

Granulosa Cells: They have a large # of FSH receptors.

FSH binding, upregulates the expression of Aromatase

Question 22

What are the two actions of Aromatase?

Answer 22

1) They convert Androstenedione –> Estrone

2) Testosterone –> Estradiol 17B

Question 23

What is the periovulatory period?

Answer 23

It is the time of onset of LH surge to ovulation; lasts about 32-36 hours

Question 24

What is the process of Luteinization?

Answer 24

In culminates in the formation of a corpus luteum.

Question 25

What three steps are emphasized in the process of progesteroe production during the luteal phase?

Answer 25

1) Increased # of LDL receptors
2) Stimulation of Choleserole Desmolase
3) Stimulation of 3B-HSD (Convering Pregneolone into Progesterone)

Question 26

What is Corpus Hemorrhagicum?

Answer 26

It is the filling of the antral cavity with blood prior to being filled with cholesterol esters from the mural granulosa cells

Question 27

What product from the Corpus Luteum further supresses FSH produciton during the Luteal Phase?

Answer 27

Inhibin A production from the Granulosa Lutein cells (part of the Corpus Luteum)

Question 28

What are referred to as the interstitial gland of the ovary and why?

Answer 28

The Thecal Cells

They retain their LH receptors and ability to produce androgens after follicular atresia