The simple idea (no memorising)
The ovary's month has three phases:
- Follicular phase (grow). FSH wakes up a batch of follicles. They grow and pour out estrogen. One follicle pulls ahead of the rest — the dominant follicle — while the others quietly fade.
- Ovulation (release). The dominant follicle bursts and releases its egg. (Concept 9 explains the trigger.)
- Luteal phase (nurture). The emptied follicle transforms into a temporary gland — the corpus luteum — which makes progesterone.
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A picture for your mind
Picture a garden. In the first half of the month, many seedlings sprout (follicles), but one strong plant wins the light and the rest wither. That winner flowers and drops its seed (ovulation). Then the plant's leftover base turns into a little compost heap that feeds the soil (the corpus luteum making progesterone).
The two halves, side by side
| First half (follicular) | Second half (luteal) | |
|---|---|---|
| Star hormone | estrogen | progesterone |
| What's happening | follicle grows | corpus luteum nurtures |
| Length | variable person to person | fairly fixed (~14 days) |
That last row is a quiet gem — we'll use it in Concept 13 to work out when ovulation happens.
Why it matters
Every "irregular cycle" problem is really a question about this play. Did a follicle grow? Did it release? Did a corpus luteum form? Naming the broken act is half the diagnosis.
Quick check ✅
- What are the ovary's three phases, in order?
- Which hormone leads the first half, and which leads the second?
Remember this 🌟
Where we're going next → What actually makes the follicle burst? A dramatic hormone spike — Concept 9.