Flashcards in Female Repro System 1 Deck (31):
Describe the structure of the most magical organ: the ovary
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
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)
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)
How do we go from oogonia to primary oocyte?
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.
So do the primary oocytes just hang out by themselves or do they get support from their fellow cells?
YEAH they get lots of support from the follicular cells. These flat cells surround the primary oocyte to make the follicle
Does every primary oocyte make it to birth?
NO, some of the primary oocytes die along the way
What is the process of continuous oocyte death called?
What is a primordial follicle, exactly?
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.
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
1. Primordial follicle-->unilaminar primary follicle
2. Follicular cells undergo mitosis and become simple cuboidal epithelium.
The unilaminar primary follicle becomes the _____________ and now the follicular cells look like ____________
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.
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.
The zona pellucida
Finally, the stromal cells RIGHT outside the multilaminar primary follicle differentiate to form _____________. What is ______________'s function.
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.
Ok so nowwww the multilaminar primary follicle turns into _____________. Describe the changes you see in this transformation.
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.
What's in the liquor? No, it's not whisky, Don and Chelsea, it's......
1. Hyaluronic acid
2. Growth factors
5. Steroids (progesterone, androstenedione, estrogens)
6. Heparan sulfate proteoglycan
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?
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
When does atresia occur most and who picks up all the dead cell parts?
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
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 _________
Still haven't ovulated, but we are close. The oocyte undergoes______________ to produce a __________ and a ___________
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.
What process does the secondary oocyte undergo after it releases the first polar body?
Meiosis II, but it stops at metaphase II. It'll stay here forever unless fertilization occurs.
WE HAVE OVULATION! What does that mean?
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.
When does ovulation occur during the 28 day menstrual cycle and what hormone's spike causes it?
After ovulation, the granules and theca internal cells reorganize into:
The corpus luteum
What hormone influences the formation of the corpus luteum
What does the corpus luteum do?
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.
What happens when the corpus luteum stops producing estrogen and progesterone?
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
What happens to the corpus luteum now that it's cells are undergoing apoptosis
Macrophages, followed by fibroblasts, will come eat up all the pieces, producing a scar of dense connective tissue called the corpus albicans
What happens to the corpus luteum if there is fertilization?
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.
What mucosa of the uterine tubes are lines with epithelium containing 2 important cell types. What are they and what do they do?
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.
Where does fertilization usually occur?
The ampulla of the uterine tube
What happens when a sperm meets the corona radiata?
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
Zona pellucida has been degraded. Describe the cortical reaction of egg and sperm rendez vous
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