The ovary is the primary female sex organ that produces the female gamete (ovum) and several steroid hormones. $A$ transverse section of the ovary reveals various developmental stages of ovarian follicles,including primary follicles,tertiary follicles (characterized by a fluid-filled cavity called the antrum),and the mature Graafian follicle. The ovary is divided into an outer cortex and an inner medulla. After ovulation,the ruptured Graafian follicle transforms into a temporary endocrine structure called the corpus luteum,which secretes progesterone. The diagram illustrates these key components: the germinal epithelium,the developing follicles,the antrum,the ovum being released,and the corpus luteum.