Endo-Repro L17 Female 1 Flashcards Preview

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Flashcards in Endo-Repro L17 Female 1 Deck (36):
1

Cortex comprises of

Follicles in stroma

2

Follicles consist of

Primary oocyte (egg) plus surrounding granulosa cells

3

Development of egg

Oogenesis

4

Stages of Folliculogenesis:

1. Primordial
2. Primary (or antral)
3. Secondary (or antral)
4. Tertiary (or pre-ovulatory)

5

Primordial


diameter
features
Additional

0.1 mm
Primary oocyte (arrested meiosis) surrounded by single layer of flattened granulosa cells
Transition is a spontaneous event

6

Primary (Pre-antral)




diameter
features
Additional

0.5-4 mm Increase in size of oocyte. Proliferation of granulosa cells. Formation of zona pellucida

Requires FSH and LH to convert to next stage

7

Secondary (antral)
diameter
features
Additional

5-20 mm
Formation of antrum and cumuls oophorus
Only after puberty

8

Tertiary (pre-ovulatory)
Additional

20-25mm
Primary oocyte resumes meiosis – increase in volume of follicular cluid.
Formation of stigma
Occurred after LH surge

9

Primordial follicles: Stage

Most primitive

10

Primordial follicles:Consists of

A primary oocyte surround by flattened granulosa cells.

11

Primordial follicles:Oocytes are formed by

Mitotic divisions of primordial germ cells and oogonia, granulosa cells derive from stroma

12

Primordial follicles:Meiosis

Primary oocytes begin meiosis but immediately stop in prophase 1

13

Primordial follicles:Location

Form a pool around the edge of the cortex.

14

Follicular atresia

• Much occurs before birth and continues through childhood so by puberty there are about 0.5 million follicles remaining.
• Not altered by pregnancy or the pill
• Accelerated by genetic disorders and chemotherapy

15

Primary (pre-antral) follicles: Formation is independent of

LH and FSH

16

Primary (pre-antral) follicles: Involves

1. Enlargement of oocyte (still in arrested meiosis)
2. Proliferation of granulosa cells
3. Formation of zona pellucida
4. Formation of theca interna

17

Secondary (antral) follicles Present in

Antrum

18

Secondary (antral) follicles Formation needs

LH and FSH

19

Secondary (antral) follicles Trigger

Slight rise of FSH causes approx. 12 to form at start of each m. cycle

20

Secondary (antral) follicles Formation involves

1. Further proliferation of granulosa cells
2. Formation of antrum
3. Activation of theca interna

21

Secondary (antral) folliclesProduces

Oestradiol

22

Secondary (antral) follicles Majority undergo

Atresia

23

Theca cell: Stimulation

LH

24

Theca cell: LH effect causes

Cholesterol via cAMP to be converted into androstenedione testosterone

25

Theca cell: Output

Androgenic effect if not aromatized in granulosa cell

26

Granulosa cell: Stimulation

FSH

27

Granulosa cell: FSH action on the cell

Testosterone converted to estradiol via aromatase

28

Steroid hormones: Derived from

C27 sterol called cholesterol

29

Steroid hormones: 3 groups and their functions

1. C21 progestogens (e.g. progesterone) → bind progesterone receptors
2. C19 Androgens (testosterone) → bind androgen receptor
3. C18 Oestrogens (e.g. oestradiol) → bind oestrogen receptor alpha and beta

30

Follicular selection:
Occurs at

day 9

31

Tertiary (pre-ovulatory, Graaffian) follicles → Amount per cycle

Only one

32

Tertiary (pre-ovulatory, Graaffian) follicles →Formation requires

LH surge (LH now targets granulosa cells → due to estrogen

33

Tertiary (pre-ovulatory, Graaffian) follicles → Involves

1. Brief further proliferation of granulosa cells
2. Luteinisation of granulosa cells
3. Swelling of follicle
4. Formation of stigma (site of rupture)
5. Resumption of meiosis

34

Tertiary (pre-ovulatory, Graaffian) follicles →Rupture

About 24hr after onset of LH surge

35

Tertiary (pre-ovulatory, Graaffian) follicles →Empty follicle forms

Corpus luteum

36

Tertiary (pre-ovulatory, Graaffian) follicles → Poor LH surge may result in

Luteinisation without ovulation, or an “inadequate” corpus luteum

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