4 - Repro - Gamete development 2 Flashcards
What causes oocytes to arrest in the Diplotene stage of prophase I?
Oocyte Maturation Inhibitor (OMI)
- from follicular cells
Which cells secrete Oocyte Maturation Inhibitor (OMI), and which stage of meiosis does this arrest oocytes in?
Follicular cells
Diplotene stage of prophase I
Why is there an increased risk of imperfect oocytes as a woman ages?
More time an oocyte is arrested in development
= increased risk of mutations
Approx how many oocytes are present when a woman reaches puberty?
~ 40,000
How many oocytes start to mature each month after a woman reaches puberty?
~ 15-20
only one fully matures each month
What are the 3 stages of oocyte maturation?
1) Pre-antral
2) Antral
3) Pre-ovulatory
What occurs in the pre-antral stage of oocyte maturation?
- Follicular cells change from simple squamous to stratified cuboidal granulosa cells
- Stromal cells form the theca folliculi (theca interna and theca externa)
Which cells form a fibrous capsule around the developing oocyte?
Theca externa
Which cells secrete the zona pellucida?
Granulosa cells
How are the granulosa cells and thecal cells arranged around the developing oocyte?
- Granulosa cells surround oocyte
- Thecal cells surround granulosa cells
What occurs in the antral stage of oocyte development?
- 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
Which cells surrounding the oocyte bind LH?
Theca interna cells
Which cells surrounding the oocyte bind FSH?
Granulosa cells
Which cells surrounding the oocyte secrete androgens?
Theca interna cells
Which cells surrounding the oocyte convert androgens to oestrogens?
Granulosa cells