Ovarian cyst

“Cyst” comes from kustis, which means “pouch”, so ovarian cysts are fluid-filled sacs on or in the ovaries. They are very common in females of reproductive age, but can affect females of any age.

The ovaries are a pair of white-ish organs about the size of walnuts. They’re held in place, slightly above and on either side of the uterus and fallopian tubes by ligaments.

Specifically, there’s the broad ligament, the ovarian ligament, and the suspensory ligament. And the suspensory ligament is particularly important because the ovarian artery, ovarian vein, and ovarian nerve plexus pass through it to reach the ovary.

If you slice the ovary open and look at it (don’t try this at home) there’s an inner layer called the medulla, which contains most of the blood vessels and nerves and an outer layer called the cortex, which has ovarian follicles scattered throughout it.

Each follicle is initially made up of an immature sex cell, or primary oocyte, which is the female sex cell, and layers of theca and granulosa cells surrounding the oocyte.

Now, there’s actually loads going on with the ovaries throughout the menstrual cycle, which is controlled by the hypothalamus and the pituitary up in the brain.

The hypothalamus secretes gonadotropin-releasing hormone, or GnRH, which makes the nearby anterior pituitary gland release follicle-stimulating hormone, or FSH, and luteinizing hormone, or LH.

In the first two weeks of an average 28-day cycle, the ovaries go through the follicular phase, meaning that out of the many follicles scattered throughout the ovaries, a couple of them enter a race to become the dominant follicle, that will be released at ovulation, while the rest regress and die off.

All the developing follicles secrete loads of estrogen, which negatively inhibits pituitary FSH, and they also make a few androgens like testosterone.