What are the roles of the ovaries?

Make an egg. The role of the ovaries is to make an egg each month which has the potential to be fertilized making an embryo, and then to support implantation of the embryo. The ovaries do this by producing an ebb and flow of hormones that interact with the pituatary gland in a complex feedback system. If implantation does not occur, the hormones decline, signaling a period to start.