Ovarian follicles

Looks like

A fluid-filled sac in the ovary, from a speck to 2 cm the day it bursts.

What it does

Grows an egg and makes the oestrogen that drives the first half of the cycle.

Keeping it well

Nothing routine; a follicle that keeps growing instead of bursting is the commonest ovarian cyst.

Related conditions

• Absent periods (amenorrhoea)
• Bone metastases and spinal cord compression
• Early puberty (precocious puberty)
• Ectopic pregnancy
• Endometriosis
• Female infertility
• Hereditary cancer syndromes (BRCA, Lynch)
• Menopause & perimenopause
• Mumps
• Ovarian cancer
• Ovarian cysts
• Ovarian torsion
• Pelvic inflammatory disease
• Polycystic ovary syndrome
• Premature ovarian insufficiency
• Premenstrual syndrome and PMDD
• Turner syndrome