- Ova (eggs) are made in the ovaries, and sperm in the testicles.
- The genetic material of the ova and sperm combine to make the characteristics of the child.
- If the ovum (egg) is unfertilised, the lining of the womb comes away (a period).
- Sperm production requires a temperature around 2 °C lower than that of the body, which is why the testicles are housed in the scrotum.
- The only function of the sperm is to fertilise a female egg and create new life.
New life begins when an egg from a woman is fertilised by sperm from a man. Eggs (ova) are made in the ovaries, and sperm in the testicles. The ovaries and testicles (gonads) also make sex hormones.
The female reproductive system
The female reproductive organs are the vagina, womb (uterus), fallopian tubes and ovaries:
- Vagina – a muscular canal around 7.5 cm long that extends from the neck of the womb to the genitals, or vulva.
- Uterus (womb) – a muscular organ, shaped like an upside down pear. Its lining is called the endometrium. The neck or entrance to the womb is the cervix, which has a small hole in its centre called the os.
- Fallopian (uterine) tubes – these tubes extend from the womb, one on each side. They both open near an ovary. These tubes carry the egg (ovum) from the ovary to the womb.
- Ovaries – two small almond-shaped glands that contain ova. Sex hormones are also made by the ovaries.
The menstrual cycle
Hormones secreted by the ovaries and a small gland in the brain called the pituitary gland control the menstrual cycle. The average menstrual cycle is around 28 days.
After a period, rising levels of the hormone oestrogen help to thicken the lining of the womb (the endometrium). At mid-cycle, an egg is released from one of the ovaries (ovulation). If the egg is fertilised on its journey down the fallopian tube, it lodges in the womb lining.
If the egg is unfertilised, falling levels of the hormone progesterone make the womb lining come away. This is called a period, or menstruation. The cycle then repeats.
When you want to have a baby you can improve your chance of getting pregnant if you know about ovulation and the ‘fertile window’ in the menstrual cycle. Read more on ovulation and the fertility window .
The egg (ovum)
A woman’s entire egg supply is developed when she is still an unborn baby. At the start of puberty, the eggs are ripened inside the ovary and one is released every month.
Each egg contains genetic material. At menopause, the ovaries stop making hormones and eggs are no longer ripened or released.
Female reproductive system problems
Some reproductive health conditions women may experience include:
The male reproductive system
The male reproductive organs are the penis, the testicles, the epididymis, the vas deferens and the prostate gland:
- Penis – contains tissue that fills with blood during sexual arousal, making the penis erect (or ‘hard’). Semen is a mixture of sperm and fluid from the male reproductive organs. It exits the penis, through the urethra, during ejaculation.
- Testicles (testes) – oval sex glands located in a skin sack called the scrotum. Sperm and sex hormones are made by the testicles. Keeping the testicles outside of the body means they have a lower temperature than the rest of the body, which is important for sperm production.
- Epididymis – a series of small tubes attached to the back of each testicle. The epididymis collects and stores sperm.
- Vas deferens – the epididymis eventually becomes the vas deferens, a larger tube that transports sperm to the urethra (the urinary passage from the bladder).
- Accessory sex glands – including the prostate gland, seminal vesicles and the bulbourethral glands. These glands contribute nourishing fluid to the sperm.
Male reproductive hormones
Hormones are chemical messengers made by glands in the body. Androgens are the hormones that make men ‘male’.
Androgens are responsible for sexual functioning, fertility and secondary sexual characteristics such as muscle mass, height, deep voice and body hair (including the beard). The most important androgen is testosterone, which is manufactured in the testicles.
The sperm
The sperm is the male reproductive cell. Its role is to fertilise an egg. It contains the man’s genetic material.
A sperm is tadpole-shaped and around 60 microns in length (one micron is a millionth of a metre). It has a lashing tail, which helps it to ‘swim’ towards a waiting egg. Sperm production continues throughout a man’s life, from puberty into old age but the quality of a man’s sperm declines from about age 45.
Male reproductive system problems
Some of the reproductive health conditions men may experience include:
Where to get help
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Overview
Each month during the years between puberty and menopause, a woman’s body goes through a number of changes to get it ready for a possible pregnancy. This series of hormone-driven events is called the menstrual cycle.
During each menstrual cycle, an egg develops and is released from the ovaries. The lining of the uterus builds up. If a pregnancy doesn’t happen, the uterine lining sheds during a menstrual period. Then the cycle starts again.
A woman’s menstrual cycle is divided into four phases:
- menstrual phase
- follicular phase
- ovulation phase
- luteal phase
The length of each phase can differ from woman to woman, and it can change over time.
The menstrual phase is the first stage of the menstrual cycle. It’s also when you get your period.
This phase starts when an egg from the previous cycle isn’t fertilized. Because pregnancy hasn’t taken place, levels of the hormones estrogen and progesterone drop.
The thickened lining of your uterus, which would support a pregnancy, is no longer needed, so it sheds through your vagina. During your period, you release a combination of blood, mucus, and tissue from your uterus.
You may have period symptoms like these:
- cramps (try these home remedies)
- tender breasts
- bloating
- mood swings
- irritability
- headaches
- tiredness
- low back pain
On average, women are in the menstrual phase of their cycle for 3 to 7 days. Some women have longer periods than others.
The follicular phase starts on the first day of your period (so there is some overlap with the menstrual phase) and ends when you ovulate.
It starts when the hypothalamus sends a signal to your pituitary gland to release follicle-stimulating hormone (FSH). This hormone stimulates your ovaries to produce around 5 to 20 small sacs called follicles. Each follicle contains an immature egg.
Only the healthiest egg will eventually mature. (On rare occasions, a woman may have two eggs mature.) The rest of the follicles will be reabsorbed into your body.
The maturing follicle sets off a surge in estrogen that thickens the lining of your uterus. This creates a nutrient-rich environment for an embryo to grow.
The average follicular phase lasts for about 16 days. It can range from 11 to 27 days, depending on your cycle.
Rising estrogen levels during the follicular phase trigger your pituitary gland to release luteinizing hormone (LH). This is what starts the process of ovulation.
Ovulation is when your ovary releases a mature egg. The egg travels down the fallopian tube toward the uterus to be fertilized by sperm.
The ovulation phase is the only time during your menstrual cycle when you can get pregnant. You can tell that you’re ovulating by symptoms like these:
Ovulation happens at around day 14 if you have a 28-day cycle — right in the middle of your menstrual cycle. It lasts about 24 hours. After a day, the egg will die or dissolve if it isn’t fertilized.
Did you know?Because sperm can live up to five days, pregnancy can occur if a woman has sex as much as five days prior to ovulation.
After the follicle releases its egg, it changes into the corpus luteum. This structure releases hormones, mainly progesterone and some estrogen. The rise in hormones keeps your uterine lining thick and ready for a fertilized egg to implant.
If you do get pregnant, your body will produce human chorionic gonadotropin (hCG). This is the hormone pregnancy tests detect. It helps maintain the corpus luteum and keeps the uterine lining thick.
If you don’t get pregnant, the corpus luteum will shrink away and be resorbed. This leads to decreased levels of estrogen and progesterone, which causes the onset of your period. The uterine lining will shed during your period.
During this phase, if you don’t get pregnant, you may experience symptoms of premenstrual syndrome (PMS). These include:
- bloating
- breast swelling, pain, or tenderness
- mood changes
- headache
- weight gain
- changes in sexual desire
- food cravings
- trouble sleeping
The luteal phase lasts for 11 to 17 days. The average length is 14 days.
Every woman’s menstrual cycle is different. Some women get their period at the same time each month. Others are more irregular. Some women bleed more heavily or for a longer number of days than others.
Your menstrual cycle can also change during certain times of your life. For example, it can get more irregular as you get close to menopause.
One way to find out if you’re having any issues with your menstrual cycle is to track your periods. Write down when they start and end. Also record any changes to the amount or number of days you bleed, and whether you have spotting between periods.
Any of these things can alter your menstrual cycle:
- Birth control. The birth control pill may make your periods shorter and lighter. While on some pills, you won’t get a period at all.
- Pregnancy. Your periods should stop during pregnancy. Missed periods are one of the most obvious first signs that you’re pregnant.
- Polycystic ovary syndrome (PCOS). This hormonal imbalance prevents an egg from developing normally in the ovaries. PCOS causes irregular menstrual cycles and missed periods.
- Uterine fibroids. These noncancerous growths in your uterus can make your periods longer and heavier than usual.
- Eating disorders. Anorexia, bulimia, and other eating disorders can disrupt your menstrual cycle and make your periods stop.
Here are a few signs of a problem with your menstrual cycle:
- You’ve skipped periods, or your periods have stopped entirely.
- Your periods are irregular.
- You bleed for more than seven days.
- Your periods are less than 21 days or more than 35 days apart.
- You bleed between periods (heavier than spotting).
If you have these or other problems with your menstrual cycle or periods, talk to your healthcare provider.
Every woman’s menstrual cycle is different. What’s normal for you might not be normal for someone else.
It’s important to get familiar with your cycle — including when you get your periods and how long they last. Be alert for any changes, and report them to your healthcare provider.