What causes an egg to mature in one of the ovaries?

An egg matures in one of the ovaries due to the influence of hormones, primarily follicle-stimulating hormone (FSH) and luteinizing hormone (LH), released by the pituitary gland. FSH stimulates the growth and development of ovarian follicles, each containing an immature egg. As the follicles grow, they produce estrogen, which further regulates the maturation process and prepares the body for potential ovulation. This hormonal interplay ultimately leads to the selection of a dominant follicle, which releases a mature egg during ovulation.