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ESA4 > 4 - Repro - Gamete development 2 > Flashcards

4 - Repro - Gamete development 2 Flashcards

1
Q

What causes oocytes to arrest in the Diplotene stage of prophase I?

A

Oocyte Maturation Inhibitor (OMI)

- from follicular cells

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2
Q

Which cells secrete Oocyte Maturation Inhibitor (OMI), and which stage of meiosis does this arrest oocytes in?

A

Follicular cells

Diplotene stage of prophase I

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3
Q

Why is there an increased risk of imperfect oocytes as a woman ages?

A

More time an oocyte is arrested in development

= increased risk of mutations

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4
Q

Approx how many oocytes are present when a woman reaches puberty?

A

~ 40,000

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5
Q

How many oocytes start to mature each month after a woman reaches puberty?

A

~ 15-20

only one fully matures each month

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6
Q

What are the 3 stages of oocyte maturation?

A

1) Pre-antral
2) Antral
3) Pre-ovulatory

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7
Q

What occurs in the pre-antral stage of oocyte maturation?

A
  • Follicular cells change from simple squamous to stratified cuboidal granulosa cells
  • Stromal cells form the theca folliculi (theca interna and theca externa)
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8
Q

Which cells form a fibrous capsule around the developing oocyte?

A

Theca externa

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9
Q

Which cells secrete the zona pellucida?

A

Granulosa cells

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10
Q

How are the granulosa cells and thecal cells arranged around the developing oocyte?

A
  • Granulosa cells surround oocyte

- Thecal cells surround granulosa cells

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11
Q

What occurs in the antral stage of oocyte development?

A
  • Granulosa cells proliferate and secrete fluid, forming the antrum
  • Theca interna cells bind LH = stimulates androgen production
  • Granulosa cells bind FSH = stimulates conversion of androgens to oestrogens
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12
Q

Which cells surrounding the oocyte bind LH?

A

Theca interna cells

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13
Q

Which cells surrounding the oocyte bind FSH?

A

Granulosa cells

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14
Q

Which cells surrounding the oocyte secrete androgens?

A

Theca interna cells

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15
Q

Which cells surrounding the oocyte convert androgens to oestrogens?

A

Granulosa cells

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16
Q

Name the 3 types of oestrogen in the female body:

A
  • Oestriol
  • Oestrone
  • Oestradiol
17
Q

Name the type of follicle produced in the antral stage of development:

A

Secondary/Graafian follicle

18
Q

What is the precursor of the androgens and oestrogens produced in the ovary?

A

Cholesterol

19
Q

When does a secondary/Graafian follicle enter the pre-ovulatory stage of development?

A

~ 37 hrs before ovulation

20
Q

What occurs in the pre-ovulatory stage of oocyte maturation?

A
  • LH receptors appear on granulosa cells, and are stimulated by the LH surge
  • LH surge restarts meiosis I
  • Oocyte arrests in Metaphase II ~ 3hrs before ovulation
21
Q

In what stage of meiosis is an oocyte arrested in, in the pre-ovulatory stage of develoment?

A

Metaphase II

22
Q

When is meiosis II of an oocyte completed?

A

Completed if the oocyte is fertilised

23
Q

At ovulation, what is the size of the follicle?

A

~ 25 mm

24
Q

What causes the follicle to rupture at ovulation?

A

LH surge

= increases collagenase activity

25
Q

If an oocyte is fertilised at the ampula, how many days does it take for it to reach the uterine lumen?

A

~ 3-4 days

26
Q

Which cells secrete progesterone?

A

Granulosa lutein cell (of the corpus luteum)

27
Q

Name the 2 types of cells in the corpus luteum:

A

1) Granulosa lutein cells

2) Theca lutein cells

28
Q

How long does the corpus luteum survive if the oocyte is not fertilised?

A

~ 14 days

Becomes corpus albicans (fibrotic scar tissue)

29
Q

The change in which hormone precipitates menstrual bleeding?

A

Decrease in progesterone

- due to death of corpus luteum

30
Q

What prevents the degradation of the corpus luteum if the oocyte is fertilised?

A

Developing embryo secrete hCG, which maintains the corpus luteum

31
Q

If fertilisation occurs, for how long does the corpus luteum secrete progesterone?

A

until the 4th month of development, as placenta can then take over

32
Q

Decribe the release of GnRH from the hypothalamus:

A

Pulsatile release ~ 1-3 hrs

33
Q

Which G- protein does LH and FSH stimulate in the gonads? Therefore which enzyme is the effector?

A

Gs

Adenylyl cyclase

34
Q

Which male hormone has a circadian rhythm?

A

Testosterone

35
Q

Which cell secretes Androgen-binding globulin (ABG), to keep testosterone in the testes?

A

Sertoli cells

36
Q

Which cells secrete inhibin?

A 
Females = granulosa cells
Males = sertoli cells
37
Q

Which hormone prevents oestrogen causing +ve feedback to the hypothalamus and anterior pituitary?

A

Progesterone

38
Q

Which female hormone causes positive feedback to the hypothalamus and anterior pituitary, precipitating the LH surge?

A

Oestrogen (at high levels)

- at low levels it causes negative feedback

ESA4 (36 decks)

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