Gametogenesis and Fertilization

Question 1

Oogenesis definition

Answer 1

Formation / Maturation of the female gamete (oocyte) by month five

Question 2

ovum (plural: ova)

Answer 2

female gamete

Question 3

oogonia

Answer 3

diploid germ cells that have potential to develop into ovum.

Question 4

Order of all the oogo shit:

Answer 4

Oogonium -> Oogonia -> primary oocyte -> secondary oocyte -> ovum (plural: ova) and second polar body -> fertilization of ovum.

Question 5

Oogenesis, step by step process.

Answer 5

1.) primordial germ cells migrate and differentiate into oogonia.
2.) Preantral (primary) follicles: increase in size, surrounding follicular cells are transformed into steroid-producing cuboidal epithelium = granulosa cells. Granulosa cells release hormones like estrogen / progesterone.
3.) Primary oocyte enters dormancy in early meiosis. REMAINS IN SUSPENDED PROPHASE I due to oocyte maturation inhibitor
4.) Secondary oocyte: way bigger, more follicle, arrested in METAPHASE II 3 hrs before ovulation.
5.) ovulation occurs, becomes ovum. (definitive oocyte). This is surrounded b y zona pellucida.

Question 6

Ovulation, step by step process

Answer 6

1.) mature ovarian follicle undergoes sudden growth spurt aka Cystic swelling.
2.) secondary oocyte ruptures out of stigma in ovary. Some of the cumulus oophorus cells rearrange corona radiata.

Middle pain signals ovulation. Day 14-18

Question 7

Corpus luteum formation and degeneration

Answer 7

1.) walls of follicle and theca folliculi (outer follicle layer) collapse.
2.) If oocyte is fertilized: progesterone secretion. prepares endometrium for implantation and maintains it.
3.) Eventual degeneration into corpus albicans
4.) if not fertilized, will become inactive in 10-14 days and menstruation occurs.

Question 8

Menstrual cycle, 3 phases

Answer 8

Menstrual phase (day 0-4) : endometrium is “sloughed off”
Proliferation phase (day 4-14) - coincides with the growth of the ovarian follicles
Secretory phase (day 14-27) - coincides with corpus luteum.

Question 9

Progesterone secretion from corpus luteum stimulates…

Answer 9

1.) epithelial increase in glycogen, increase thickening in endometrium, and increase coiling of spiral arteries.

Question 10

What happens if fertilization does not occur, or if implantation is successful?

Answer 10

If fertilization does not occur, the menstrual phase begins with. . .
1) the corpus luteum degenerating due to …
2) decrease in estrogen and progesterone levels (initiates ‘sloughing’)

If implantation is successful (gravid phase), then…
1) cleavage of the zygote begins and
2) the blastocyst begins to implant.
3) Human chorionic gonadotropin keeps the corpus luteum
secreting progesterone > estrogen and
4) the luteal phase (thickening of uterine lining) continues with no menstruation

Question 11

Ovulatory surge occurs due to what?

Which hormone spikes due to ovulation?

Answer 11

Ovulatory surge: reactivation of meiosis

Luteinizing hormone (LH) = spike in ovulation during proliferative phase.

Question 12

Phases of Fertilization

Answer 12

1.) Penetration of corona radiata
2.) Penetration of the zona pellucida
3.) Fusion of cell membranes: causes 2 things:
a.) formation of calcium wave radiating over surface of egg
b.) release thousands of small cortical granules.
Causes cortical reaction (impenetrable by other spermatozoa and the oocyte resumes Meiosis II.

Question 13

Results of fertilization:

Answer 13

1. Diploid
2. Genetic sex
3. Cleavage