In the context of reproduction, an antrum is Select one: a recess at the entrance to the cervix a cavity in a blastocyst the hollow center of the corpus luteum a fluid-filled cavity in a Graafian follicle Solution Correct option. D. The cavity where antral fluid of the developing ovarian follicle accumulates is called antrum (means- cavity). During growth of tertiary follicles, TF, (antral TF, 200 M resting TF, 1-9 mm ripe TF, 10-14 mm Graffian follicle, 15-20 mm) several antral cavities may develop in a single follicle. As the follicle matures (near ovulation) all the antral cavities finally coalesce forming a single large antrum in the Graffian follicle. Option. A. Incorrect- Antrum is the central cavity of developing ovarian follicles. It is NOT the entrance of cervix. Option. B. Incorrect. Antrum is the central cavity of developing ovarian follicles Option. C. Incorrect. After ovulation, the granulosa cells and cells of theca interna of the ovulated Graffian follicles form corpus luteum. It secretes estrogen and progesterone, thus the level of these hormones in blood rises. However, the term ‘antrum’ is limited to intact Graffian follicle. Once Graffian follicle ruptures during releases of ovum from it, the cavity (antrum) is lost, too..