Female Repro System 1

Question 1

Describe the structure of the most magical organ: the ovary

Answer 1

From the outside in:

1. Surface epithelium (simple cuboidal)
2. Tunica albuginea (dense connective tissue capsule)
3. Cortex: stroma with follicles at different levels of development
4. Medulla: loose connective tissue with blood vessels entering from the hilum

Question 2

Ok so we’ve go fertilization. Yay! How does this to-be baby girl start to make her own eggs (or should I say, oogonia, for now)

Answer 2

1. 1st month: primordial germ cells migrate from yolk sac to gonadal primordia
2. In gonadal primordia, the cells divide and differentiate as oogonia (only get 7 million by month 5 nbd)

Question 3

How do we go from oogonia to primary oocyte?

Answer 3

Oogonia start to go through meiosis, but STOP at prophase of meiosis I (they get really far, I know). This process starts at month 5 and by birth, all the oogonia are primary oocytes in prophase I.

Question 4

So do the primary oocytes just hang out by themselves or do they get support from their fellow cells?

Answer 4

YEAH they get lots of support from the follicular cells. These flat cells surround the primary oocyte to make the follicle

Question 5

Does every primary oocyte make it to birth?

Answer 5

NO, some of the primary oocytes die along the way

Question 6

What is the process of continuous oocyte death called?

Answer 6

Atresia

Question 7

What is a primordial follicle, exactly?

Answer 7

It is what we call the primary oocyte surrounded by a single layer of follicular cells formed during fetal life. The follicular cells are surrounded by a basal lamina that separates it from the stroma.

Question 8

Now baby is born and we fast forward to puberty, the wonder years. Some of the primordial follicles get chosen to grow and differentiate into mature follicles (may the odds be ever in your favor).

What does the primordial follicle turn into and how does it change

Answer 8

1. Primordial follicle–>unilaminar primary follicle

2. Follicular cells undergo mitosis and become simple cuboidal epithelium.

Question 9

The unilaminar primary follicle becomes the _____________ and now the follicular cells look like ____________

Answer 9

1. Multilaminar primary follicle
2. Stratified follicular epithelium made of GRANULOSA cells that communication via gap junctions.

*Note, follicular cells now called granulosa cells. Just because.

Question 10

In the multilaminar primary follicle something else starts to form between the primary oocyte and the granulosa cells. It has the important role of being a sperm receptor and serving as the acrosomal activator

Yes, this card is in fact Jeopardy style. Just keeping it fresh for ya.

Answer 10

WHAT IS:

The zona pellucida

Question 11

Finally, the stromal cells RIGHT outside the multilaminar primary follicle differentiate to form _____________. What is ______________’s function.

Answer 11

1. Theca interna
2. Function: Secretes androstenedione (remember from steroid synthesis!) which diffuses across the basement membrane to the granulosa cells that contain aromatase, which converts it to estrogen.
3. This estrogen returns to the theca (which is highly vascular) and gets distributed throughout the body.

Question 12

Ok so nowwww the multilaminar primary follicle turns into _____________. Describe the changes you see in this transformation.

Answer 12

1. Vesicular/antral follicle.
2. The granulosa cells start to secrete fluid (follicular fluid or liquor folliculi if you’re fancy) which makes lots of space between the cells.
3. The granulosa cells eventually rearrange themselves around a larger cavity called the antrum.
4. The surrounding stroma cells also now form a theca externa.

Question 13

What’s in the liquor? No, it’s not whisky, Don and Chelsea, it’s……

Answer 13

1. Hyaluronic acid
2. Growth factors
3. Plasminogen
4. Fibrinogen
5. Steroids (progesterone, androstenedione, estrogens)
6. Heparan sulfate proteoglycan

Question 14

Now our little follicle is almost ready for action. In it’s last transformation (for now) it becomes a _____________. What changes occur during this transformation?

Answer 14

1. Mature/Graafian follicle
2. Granulosa cells around the oocyte form a hillock called the cumulus oophorus
3. The corona radiata is formed from the granulosa cells surrounding the zona pellucida

Question 15

When does atresia occur most and who picks up all the dead cell parts?

Answer 15

1. Occurs during times of big hormonal changes so right after birth (losing all that maternal hormone power), during puberty and during pregnancy.
2. Macrophages followed later by fibroblasts

Question 16

Right before ovulation, the dominant follicle will be buldging against the tunica albuginea just dyingggg to get out. This produces a white/transluent ischemic area called then _________

Answer 16

Stigmata

Question 17

Still haven’t ovulated, but we are close. The oocyte undergoes______________ to produce a __________ and a ___________

Answer 17

1. Process: meiosis I completion
2. Makes a secondary oocyte and the first polar body.

*Note: the secondary oocyte and first polar body both have the same DNA (remember meiosis I has DNA replication) but the secondary oocyte has almost all the cytoplasm. That greedy bastard.

Question 18

What process does the secondary oocyte undergo after it releases the first polar body?

Answer 18

Meiosis II, but it stops at metaphase II. It’ll stay here forever unless fertilization occurs.

Question 19

WE HAVE OVULATION! What does that mean?

Answer 19

The oocyte+corona radiate+follicular fluid are released from the ovary. But the oocyte doesn’t get far and adheres loosely to the ovary surface and is drawn into the fallopian tube.

Question 20

When does ovulation occur during the 28 day menstrual cycle and what hormone’s spike causes it?

Answer 20

Day 14

LH spike

Question 21

After ovulation, the granules and theca internal cells reorganize into:

Answer 21

The corpus luteum

Question 22

What hormone influences the formation of the corpus luteum

Answer 22

LH

Question 23

What does the corpus luteum do?

Answer 23

Under the influence of LH, the new modified granulosa and theca interna cells produce progesterone and continue to use aromatse to convert androstenedione to estradiol. This continues for 10-12 days after ovulation, at which point it stops. Without fertilization and take over from the placenta, progesterone levels will fall.

Question 24

What happens when the corpus luteum stops producing estrogen and progesterone?

Answer 24

Estrogen usually inhibits FSH (so that another follicle doesn’t start forming while we’re still waiting to see what happens to the one that ovulated). Without it: FSH is released from the anterior pituitary and another follicle starts to develop.

Progesterone maintains the endometrial lining. Without it: menstruation occurs

Question 25

What happens to the corpus luteum now that it’s cells are undergoing apoptosis

Answer 25

Macrophages, followed by fibroblasts, will come eat up all the pieces, producing a scar of dense connective tissue called the corpus albicans

Question 26

What happens to the corpus luteum if there is fertilization?

Answer 26

The corpus luteum stays for 4-5 months. How? hCG is produces by the trophoblast cells of the implanted embryo, which maintains the corpus luteum so that it continues to produce progesterone and prevent the endometrium from shedding. By 4-5 months, the placenta takes over the progesterone production. Then the corpus luteum dies and becomes the corpus albicans.

Question 27

What mucosa of the uterine tubes are lines with epithelium containing 2 important cell types. What are they and what do they do?

Answer 27

1. Cilitated cells: the cilia elongate during the follicular phase and atrophy in the late luteal phase. They sweep the egg towards the uterus.
2. Secretory peg cells: nonciliated cells that often stain darkly, they secrete glycoproteins making a mucus film that covers the epithelia.

Question 28

Where does fertilization usually occur?

Answer 28

The ampulla of the uterine tube

Question 29

What happens when a sperm meets the corona radiata?

Answer 29

1. The acrosomal reaction happens: hyaluronidase is released from the sperm head, allowing the sperm to move easily to the zona pellucida.
2. Sperm surface proteins activate acrosin, a protease on the acrosomal membrane that degrades the zona pellucida

Question 30

Zona pellucida has been degraded. Describe the cortical reaction of egg and sperm rendez vous

Answer 30

Cortical reaction: The 1st sperm in fuses with the oocyte and triggers Ca2+ release from vesicles, causing cortical granule release of proteases. This happens all over the oocyte, making a perivitelline barrier that keeps all other spermies out

Question 31

What happens to the secondary oocyte now that the sperm has met up with it

Answer 31

It completes meiosis II, making a second polar body and the female pronucleus of the haploid ovum. This joins with the sperm head that decidedness into the male pronucleus.

Male pronucleus+female pronucleus=ZYGOTE. WE HAVE LIFTOFF WHOOOOO