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Follicular Phase
- Primordial follicles developed in ovary before birth
- Arrested development in prophase at diplotene
- Few follicles each day start growing,
- Move into primary (pre-antral) stage
- Then antral (Graafian) stage
- Finally pre-ovulatory
- Pre-ovulation started by surge of LH
- Meiosis finishes, cortical granules produced
- Follicular fluid volume increases, follicle bursts and fluid contents (including oocyte)
shed onto surface of ovary.
- Oocyte collected by fimbria of oviduct. Cilia wash through.
- Follicle collapses to form corpus luteum
Luteal Phase
- LH, FSH fall to negligible levels
- Fibrin core formed in follicle
- Membrana propria breaks down
- Corpus luteum increases secretion of progestagens, (granulosa cells become large, rich
in mitochondria, SER, lipid droplets, Golgi bodies and lutein (yellow colour))
- Small cells derived from thecal cells secrete androgens which are used as substrate by
large cells.
- Large cells secrete progesterone, oxytocin.
- Inhibin promotes production of progesterone
- corpus luteum maintained by low levels of LH
- luteolysis occurs eventually unless pregnancy ensues
- in pregnancy hCG from blastocyst maintains corpus luteum
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