VMBO Year 2 · HAVO/VWO Years 2–3 · Reproduction and sexuality · Section 4.3

Becoming fertile

Fertility

During puberty, reproductive systems mature and may become fertile, meaning able to contribute to reproduction. Sperm production begins in the testes, while egg cells already present in the ovaries begin maturing in cycles.

Sperm production

From puberty, often around the early teenage years, the testes produce millions of sperm cells under hormonal control. The scrotum helps keep them slightly cooler than core body temperature, which supports sperm production.

Sperm mature and are stored temporarily in the epididymides, then travel through the sperm ducts.

The seminal vesicles and prostate gland add fluid, including substances supporting sperm. Together the fluid and sperm form semen; sperm cells make up only a small part of its volume.

Semen leaves through the urethra in the penis. Sperm production may continue into older age, although fertility can change.

Egg maturation

The ovaries contain many immature egg cells from before birth. From puberty, usually one egg matures and is released during a cycle, often about once a month.

Ovulation is the release of an egg from an ovary. It enters an oviduct and travels towards the uterus. An egg is usually capable of being fertilised for about 12–24 hours after ovulation. If fertilised, it can begin developing and later implant in the uterus.

Menstruation

The uterine lining develops during the cycle in preparation for a possible pregnancy. If pregnancy does not occur, changing hormone levels cause part of this lining to break down and leave through the vagina with blood: menstruation, or a period.

The first period often occurs between about 10 and 16 years, but timing varies. Symptoms also vary and can include cramps, headache or mood changes.

Endometriosis is a condition in which tissue similar to the uterine lining grows outside the uterus. It can cause severe period pain and other persistent symptoms.

The menstrual cycle

A 28-day cycle is a useful school model, not a rule for everyone. Day 1 is the first day of menstruation. In a 28-day example, ovulation is around day 14. The lining develops before ovulation and is maintained afterwards in preparation for implantation.

If pregnancy does not occur, hormone levels fall and the next period begins. Cycles are often irregular in the first years after periods start.

During perimenopause, hormone levels and cycles change. Menopause is the final menstrual period, recognised retrospectively after 12 months without periods for another reason; it usually occurs in midlife.

Period products

Products for collecting or absorbing menstrual blood include:

• Pads: Disposable or washable materials worn outside the body.
• Period underwear: Underwear with absorbent layers.
• Tampons: Absorbent products placed in the vagina.
• Menstrual cups: Reusable cups that collect blood and are emptied and cleaned according to the manufacturer's instructions.