Oogenesis

Question 1

How many oocytes are in the ovary after birth compared to before puberty hits?

Answer 1

400,000 after birth
40,000 before puberty
- arrested in the diplotene stage of meisis

Question 2

What two points does meiosis arrest in oogenesis?

Answer 2

Arrested in the diplotene stage of prophase after birth, primary oocyte

Arrested at metaphase II, after ovulation - secondary oocyte and polar body I

Question 3

When is the first mieotic division complete in oogensis?

Answer 3

After puberty before ovulation. Primary oocyte

Question 4

Describe follicle development

Answer 4

In Fetal period: diploid oogonium without follicle

Later fetal period - birth: primary oocyte in diploid stage of meiosis and primordial follicle, some flattened follicle cells. 2 chromoids/chromosome

Birth to puberty: diploid primary oocyte and primary follicle - single layer of cuboidal follicle cells

After puberty:
meiosis resumed to metaphase II in some primary oocyes.
Secondary follicle forms with miltiple layer of follicle cells, antrum formation. Granulosa surrounds outside follicle cells
Secondary oocyte (haploid) + polar body, -> teriatry follicle: multilayers of follicle cells, corona radiata and large antrum

Question 5

Components of a mature follicle

Answer 5

Tertiary Follicle

Theca externa: produce angiogenesis factor

Theca interna: LH receptors, secrete testosteone

Membrana granulosa

Mural granulosa cells: develop FSH receptos, synthesize aromatase, converts testorone to 17Beta-estradiol, estrogens stimulate formation of LH on granulosa cell

Antrum

Culumus cells facilitate release of ovum at ovulation

Zona pellucida

Oocyte

Question 6

When does meiosis of an oocyte complete?

Answer 6

After fertilization, second meiotic division completes and second polar body formed

I chromotid

Question 7

When does ovulation of the ovum from the ovary and mature follicle occur?

Answer 7

At metaphase II, follicle stay behind

Question 8

What is the corona radiata and zona pellucida?

Answer 8

Corona radiata is a layer of follicle cells surrounding oocyte

Zona pellucida: non-cellular membrane, secreted by corona radiata and oocyte

Question 9

What factors cause meiosis to arrest at the diplotene stage of prophase I?

Answer 9

High conc of cAMP from oocyte and follicular cells
-inactivates MPF (maturation promoting factor)

CGMP from follicular cells, inactivate phophdiesterase 3A in oocyte

Question 10

What mechanisms are used to move the egg in the uterine tube?

Answer 10

Contraction of tubal smooth muscle

Slow - ampulla, 72 hours

Fast - isthmus, 8 hours requires progestrone

Uterine arrival: 3-4 days.

Question 11

Whats required for fast transportation of the egg?

Answer 11

Progestrone