Anatomy
Each follicle is a small fluid-filled structure housing an immature egg and the cells that nourish it. Follicles are counted and measured on ultrasound during monitoring, and their size guides the timing of the trigger injection. A visible follicle does not guarantee a mature egg will be collected from it.
Also known as: ovarian follicle, follicles
Related Australia guides
Planning tools
Sources
- Healthdirect Australia (healthdirect.gov.au)
- Pregnancy, Birth and Baby (pregnancybirthbaby.org.au)
Last reviewed: 10 September 2026. Written by the Antega Editorial Team. General information only — always follow the advice of your own clinic, doctor or pharmacist.