How the Ovary Repeats Each Cycle

The ovarian cycle repeats each month and drives key changes in the menstrual cycle. It has two main phases: the follicular phase and the luteal phase. Ovulation, which is triggered by a surge in luteinizing hormone (LH), separates these phases.

The follicular phase is the more variable part of th...

The ovarian cycle mainly consists of the follicular and the luteal phases.

In the follicular phase, a primordial follicle is transformed into a primary follicle. The primary oocyte within this follicle secretes a glycoprotein-rich extracellular layer — the zona pellucida — around it.

The primary follicle then develops multiple laye...