For ovulation to occur, the ovary must produce estrogen and progesterone in response to FSH release multiple primary follicles that become dominant follicles a single primary follicle that becomes a graffian follicile at least one mature secondary follicle

The process of ovulation involves several steps and hormones. Here's a step-by-step explanation:

1. The menstrual cycle begins with the follicular phase. The pituitary gland releases Follicle Stimulating Hormone (FSH). This hormone stimulates the ovaries to produce around 5 to 20 small sacs called follicles. Each follicle contains an immature egg.

2. Usually, only one follicle will mature into a dominant follicle. The dominant follicle produces estrogen.

3. The rise in estrogen levels signals the pituitary gland to reduce the production of FSH and start producing Luteinizing Hormone (LH).

4. The surge in LH triggers ovulation, which is when the dominant follicle releases its egg. This follicle is now called the Graafian follicle.

5. After ovulation, the Graafian follicle transforms into the corpus luteum, which produces progesterone. Progesterone prepares the uterus for potential pregnancy.

So, to answer your question, for ovulation to occur, the ovary must produce estrogen in response to FSH release, a single primary follicle must become a Graafian follicle, and at least one mature secondary follicle (the Graafian follicle) must be present.