Estradiol chemical structure?

Estradiol (17β-estradiol) is a steroid hormone with four fused rings (A–D) in a classic steroid nucleus. Key features:
- Molecular formula: C18H24O2
- A ring is a phenolic/aromatic ring with a hydroxyl group at position 3
- A second hydroxyl group is at the 17β position on the D ring
- Overall, it is the primary natural estrogen in humans

If you need a specific format of the structure, I can provide:
- A downloadable 2D structure image
- The SMILES string for computational use
- The InChI/InChIKey for database queries

Which format would you like?