Producing an egg ready for fertilization each month is a multi-step process that links several organs in the body.
The hypothalamus at the base of the brain releases GnRH, which stimulates the pituitary gland to release follicle-stimulating hormone (FSH) and luteinizing hormone (LH).
FSH stimulates a group of primordial follicles in the ovary to grow. Growth begins as extra layers of granulosa cells form around the egg; nearby ovarian tissue then develops into theca cells, which separate into an inner layer (theca interna) and an outer layer (theca externa). At this stage the follicle is called a primary follicle.
Under the influence of LH, the theca cells convert cholesterol into androstenedione, which passes into the granulosa cells. Helped by FSH, the granulosa cells use the enzyme aromatase to convert androstenedione into estrogen. Fluid secreted by the follicle cells collects in a central cavity, and the follicle is now called an antral follicle.
Rising estrogen from the growing follicles reduces FSH release. As a result, the other follicles stop growing and fade away, except one: the dominant follicle, which has the most FSH receptors and can respond to even small amounts of FSH. The very high estrogen level around mid-cycle triggers a sudden surge of LH, which completes the maturation of the egg. About 36 hours after the surge begins, the egg is released from the follicle: this is ovulation. Just before ovulation, the mature follicle is called a Graafian follicle.
The mature egg leaves the ovary surrounded by a few supporting (corona) cells and is picked up by the finger-like fringes of the fallopian tube. The remainder of the follicle becomes the corpus luteum, which produces progesterone. Progesterone completes the build-up of the uterine lining and changes its structure to prepare it to receive and implant a fertilized egg. If pregnancy does not occur, estrogen and progesterone levels fall, the lining breaks down and is shed as a menstrual period.
The part of the ovarian cycle before ovulation is called the follicular phase, and the part after ovulation is the luteal phase.
International Guidelines
In line with global standards, Dr. Sabry follows the latest recommendations from the American Society for Reproductive Medicine (ASRM), European Society of Human Reproduction and Embryology (ESHRE), and Royal College of Obstetricians and Gynaecologists (RCOG). Thus, patients receive care that is safe, ethical, and evidence-based.
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Why Choose Dr. Ashraf Sabry?
Dr. Ashraf Sabry, consultant in obstetrics, gynecology, fertility, and aesthetic gynecology, is recognized among the best OBGYN and fertility specialists in Cairo. With over 20 years of experience, he combines science and compassion to provide world-class care. Book your appointment through the contact page, WhatsApp, or call +201022224442.