The simple idea (no memorising)
Each growing egg sits in a little sac called a follicle. The follicle has two layers of worker cells, and they cooperate like a two‑station kitchen:
- Theca cells (outer layer) listen to LH. Their job: make androgens — the raw ingredient.
- Granulosa cells (inner layer) listen to FSH. Their job: take those androgens and, using an enzyme called aromatase, convert them into estrogen — the finished dish.
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The single sentence that unlocks it
Say it a few times. Almost every later puzzle — PCOS, infertility, menopause — becomes easy once this sentence is automatic.
A tidy table
| Hormone | Which cell it talks to | What that cell makes |
|---|---|---|
| FSH | granulosa | grows the follicle; makes estrogen |
| LH | theca | makes androgens (the raw material) |
FSH also does one more kind thing: it keeps the follicle alive, protecting it from fading away too early.
Why it matters
Look what happens if the raw material (androgen from theca) piles up but doesn't get converted well: you'd get too much androgen and poor egg development. Hold that thought — it is exactly the engine of PCOS in Part 3.
Quick check ✅
- Which cell listens to LH, and what does it make?
- What does aromatase do?
Remember this 🌟
Where we're going next → We keep mentioning estrogen and progesterone. What do these two hormones actually do? Concept 7.