Synonym for preovulatory follicle. A large, mature tertiary follicle that will respond to an adequate LH surge or injection of human chorionic gonadotropin (hCG) by undergoing ovulation, releasing its egg. Produces estradiol and, with exposure to LH or hCG, progesterone. Named after Reijnier de Graaf (1641-1673), the first person to see and to appreciate the importance of the ovarian follicle.

A fluid-filled space between the follicle cells, the development of which marks the transformation of a tertiary follicle from a secondary follicle. Composes the bulk of the mature, preovulatory follicle (sometimes called the Graafian follicle) and very obvious on transvaginal ultrasound scanning during monitoring of follicular development as dark, "echolucent" spaces within the ovary.

Latin for yellow body, the description being that of the solid or cystic structure in the ovary after ovulation. Derived from the ovulating Graafian follicle. At first red and friable as arteries and veins invade the collapsed follicle, it soon matures into a gland that is very efficient at producing progesterone, a hormone that's soluble in the fat and which therefore gives the corpus luteum its yellow color. Provides its name to the second, or luteal phase of the ovarian cycle, as well as to luteinising hormone, which causes the corpus luteum to be formed and sustains it until, in the event of pregnancy, it is supported instead by human chorionic gonadotropin. The appearance of the corpus luteum on transvaginal ultrasound is so variable (and so able to be confused with a serious abnormality of the ovary) that for accurate diagnosis of such pathology it is best to scan in the follicular phase or while taking a progestogen to prevent formation of this structure. Plural: corpora lutea.

The preovulatory follicle, or Graafian follicle, that has won the responsibility for producing estradiol for the rest of that particular ovarian cycle. Chosen by the end of the first week of the follicular phase. Its destruction (whether accidental or intentional) means that a new follicular phase must start, with ovulation two weeks later, whereas destruction of one of the tertiary follicles before one has become dominant causes no interference with the timing of ovulation for that cycle.

The equivalent of the menstrual cycle in the ovary, comprising the follicular phase and the luteal phase. Thus the ordered sequence of timely development of tertiary follicles to a (usually) single dominant follicle or Graafian follicle, characterised by increasing production of the estrogen estradiol), through ovulation, when estradiol falls and progesterone starts to rise, followed by the development and then decline of the corpus luteum, with the further production of progesterone. Because estradiol and progesterone control the growth and development of the endometrium in the uterus, the ovarian cycle determines the menstrual cycle (normally lasting from 24 to 35 days in length, and with a typical duration of about 28 days) and also the cycle of the normal female hypothalamus and pituitary gland.