You are here
Puberty and Sexual Organs
It’s good to get really well-informed about bodies, both your own and others. This can help you to be sexually healthy, confident and know what changes occur during puberty.
Not everyone fits simply into one of the categories ‘girl’ or ‘boy’, and there is help out there for young people who think they may be ‘transgender’ where they have a girl’s body but feel like a boy, or the other way around. If you have experienced this, you may find this site useful.
What is puberty?
Between the ages of 10 and 14 most boys and girls begin to notice changes taking place in their bodies. These changes, which occur over a number of years, are generally referred to as puberty.
The changes take place in all boys and girls but they will start at different times and take place at different rates. Not everyone starts puberty between the ages of 10 and 14, some people start younger, and some much later. Similarly, in some people all the changes take place in two years, and in others they can take as long as four years. Generally they start between ages 7 and 13 in girls and ages 9 and 15 in boys.
Puberty starts when extra amounts of chemicals called hormones start to be produced in the body. These hormones guide the changes that take place in the body. As well as causing physical changes these hormones also cause emotional changes.
One of the main physical changes of puberty is the growth and development of the sex organs – the parts of the body that are used to have sex and make babies. Sex organs that can be seen on the outside of the body are called ‘genitals’ while those that are inside the body are usually called ‘reproductive organs’.
Some more about a girl’s sex organs
Between a girl’s legs there are three small openings. At the front is the urethral opening which a girl urinates through, and at the back is the anus which she defecates from. In between these two openings is a third, her vaginal opening.
From the vaginal opening there is a small passageway or tube, called the vagina, which leads to the reproductive organs inside the body.
Periods - when a girl has her period the blood comes out through her vagina. Inside the vagina there is a small piece of thin skin called the hymen. The hymen partly covers the vaginal opening, but there is still enough of a gap for blood to get through. Sometimes the hymen breaks and bleeds slightly when a girl has sex for the first time. There is more information about a girls period below.
Some other important parts of a girl’s sex organs are:
- The clitoris, which is at the front of a girl’s outside sex organs and is about the size of a pea. The purpose of the clitoris is to give sexual pleasure. It is very sensitive and important for sexual activity.
- The outer lips (labia) of a girl’s sex organs.
Breasts grow into a variety of shapes and sizes, and many girls' breasts remain small throughout their adult lives. It is also normal for one breast to grow faster than the other. Usually breasts become more even as they reach full development. However, most girls' breasts will always be slightly uneven in shape and size.
Some more about a boy’s sex organs
A boy’s sex organs outside his body are his penis and testicles (testes). A boy’s penis hangs down between his legs at the front of his body. The main parts of a penis are:
- The shaft - the main, long part of the penis
- The glans - the tip or head of the penis
- The foreskin - skin which covers the glans
Underneath the penis is the scrotum – a loose, wrinkly pouch of skin that hangs down behind a boy’s penis. It contains his testicles.
As a boy goes through puberty his penis will grow bigger and longer, and his testicles move lower down his scrotum. Sometimes one testicle grows faster than the other, and it is natural for one to hang lower than the other. Pubic hair will also start to grow at the base of his penis.
The foreskin can usually be pulled back quite easily. If it is tight it can be stretched by gently pulling it over the glans. All boys are born with a foreskin, but some have it removed when they are a baby, or later in life. The removal of the foreskin is called circumcision. Circumcision happens for religious or cultural reasons, or for health reasons, such as to reduce the likelihood of becoming infected with HIV.
Erections - when a boy's penis hardens and lengthens it is known as an erection. This usually happens when a boy has romantic or sexual thoughts, or as a result of physical stimulation. However, during puberty a boy will start to get erections more often, sometimes without any stimulation at all.
Most erections are not straight, and tend to either curve upwards or to either side. Many boys worry that their penis is smaller than other boys', but most penises are around the same size when erect.
Wet dreams - erections can happen at any time, including when a boy is asleep. A wet dream happens when a boy becomes sexually aroused while he is asleep and ejaculates (semen - the sticky liquid that sperm is part of - is released through his penis). Sometimes boys can remember having had a sexual dream. But often they just notice a wet patch on their nightclothes or on the sheets when they wake up.
Wet dreams are not something to be embarrassed about; they are natural and happen to lots of boys. There is also no need to worry about not getting wet dreams as not everyone does.
Eggs and Sperm
Inside a girl’s body are two small organs called the ovaries. Contained in these ovaries are hundreds of tiny sex cells called eggs, each no bigger than the head of a pin. At some point during puberty, the ovaries will begin to release these eggs. Usually one egg is released every month. This process is called ovulation.
A boy’s sex cells are called sperm and they are even smaller than a girl’s eggs. At puberty a boy's testicles will start making sperm. Sperm leaves a boy's body through his penis when it is hard and erect. This is known as ejaculation and it happens when a boy reaches the height of sexual excitement and has an orgasm. When a boy ejaculates, millions of tiny sperm are sent from his testes, up through his penis and out through the end. The sperm are contained in a sticky white fluid called semen.
When a boy’s sperm meets with a girl’s egg they usually join together, which is called fertilisation. The fertilised egg may then become a fetus, the first stage in the growth of a baby.
How do egg and sperm meet? – sexual intercourse
The most common way that sperm get inside a girl’s body is through sexual intercourse. Sexual intercourse is when a boy puts his hard erect penis inside a girl's vagina. It is also often called having sex or making love.
Having sex (which usually involves moving the penis in and out of the vagina) is usually pleasurable for both a boy and a girl, and it will often result in an orgasm for one or both partners. If a boy ejaculates while his penis is inside the girl’s vagina (or if semen gets inside the vagina any other way) then the millions of tiny sperm in the semen will swim up the vagina, through the cervix (the entrance to the uterus) and into the uterus (also known as the womb). From there they will swim into the fallopian tubes. In one of the fallopian tubes the sperm may find an egg that has recently been released by the ovary. The sperm will surround this egg and try to get inside it. Eventually just one sperm cell will succeed, and the egg and sperm will join. This joining is also known as fertilisation or conception.
This joined sperm and egg then travel back down to the uterus, where they will settle in the thick, blood-rich lining and start to grow. Once the fertilised egg has settled in the uterus and is growing, we say a girl is pregnant.
What happens if the sperm and the egg don’t meet? - periods
On average, the whole menstrual cycle (from the first day of the period to the day before the next) will last 28 days.
Girls generally only release an egg once a month, and it will normally take a few days to travel down the fallopian tube. If the sperm and the egg don't meet to become a fertilised egg during this time, then she won’t become pregnant.
Without a fertilised egg to nourish, the thick lining of the uterus is no longer needed. So, approximately 14 days after a girl’s egg is released, the bloody lining of the uterus will begin to come away, and will flow down through the cervix and out of the vagina. This process is called menstruation, and this is the blood that a girl will notice when she has her period. During puberty, a girl’s first period is a sign that she has released her very first egg, and could now have children.
Periods will usually last somewhere between 3 and 10 days. Around 14 days after the start of her last period, a girl will ovulate (release an egg) again, and will once again have the chance to become pregnant. This process of period, then ovulation, then period, is known as the menstrual cycle. On average, the whole menstrual cycle (from the first day of the period to the day before the next) will last 28 days, although variations between 21 and 35 days are quite normal.
More about pregnancy
Though an egg is usually released about the same time each month, this doesn’t mean that a girl can predict exactly when she will (or won’t) become pregnant. This is because girls usually have no way of knowing exactly when they are ovulating. Not only can the day of ovulation vary from girl to girl, it can vary from month to month in an individual girl.
In addition, sperm can survive for several days within the body, so they can ‘hang around’ waiting for an egg to be released if there isn’t one there already.
All this means that if a girl wants to avoid pregnancy but still have sex, she and her partner will need to use contraception. Sexually transmitted diseases, which can be passed on from one person to another during sexual intercourse, are also something that both boys and girls need to consider if they decide to have sex. Condoms are widely used because they help to prevent both pregnancy and sexually transmitted diseases.
Using contraception every time you have sex is very important if you want to avoid pregnancy. It is also important to remember that a girl can become pregnant even if:
- It is the first time she has sexual intercourse
- She has sex before she has her first period (it could be that she is ovulating for the first time)
- She has sex during her period (sperm can stay alive for several days)
- A boy withdraws his penis before he ejaculates (pre-come, the fluid that leaks out the penis before a boy ejaculates, can sometimes contain sperm)
- She has sex standing up (sperm can swim in any direction – up or down!)
Because periods stop during pregnancy, the first sign that a girl may be pregnant is usually a missing period. If a girl doesn’t start her period at the usual time, it is probably a good idea for her to talk to her doctor or another adult as soon as she can. Periods can come late for other reasons (for example when a girl is stressed, on a very strict diet or has been unwell), but if she has had sex in the past month, then it may be a good idea to take a pregnancy test to be sure.
Sexual feelings and your body
When boys get sexually excited, the main sign is that they get an erection. For both boys and girls when they are sexually excited or "turned on", extra blood comes to the surface of the skin, particularly around the penis and vagina. This can cause areas of the body to feel more sensitive, and some people find they get a warm sensation.
Sexual feelings and masturbation
A person can have sexual feelings any time in their life, but these change around puberty. You might find some sexual feelings just seem to happen to you. But sexual feelings mostly come about from things you choose to do, either on your own or with someone else.
A main way that people express their sexual feelings is by touching their own genitals. Boys can get pleasure from touching their penis, particularly the tip. Girls can get pleasure by rubbing their clitoris and vulva and/or moving one or several fingers up and down inside their vagina. This is called masturbation. Some people masturbate very often, maybe every day. Some people do it less often, and some don't masturbate at all.
When a person is masturbating they become more and more sexually excited. They may then reach a peak of sexual excitement which is called having an orgasm or "coming". This is when all the tension and excitement that has built up is suddenly released. Boys ejaculate when they have an orgasm and their penis will then go limp. Everybody has their own way of masturbating that feels good for them. For many, masturbation is their first sexual experience.
There are many myths about masturbation which make some people think it is wrong. However, masturbation is a normal and natural activity and is not bad for you unless you masturbate so much that you make your genital area sore. Masturbation does not damage you health: it cannot cause cancer, give you a sexually transmitted infection, affect your eyesight, or make you go mad. It does not cause hair to grow on your palms or any other part of your body, and it doesn't stunt your growth. If it did, the vast majority of people in the world would be very short and unhealthy!
People have strong views on it, but pornography is one way that some young people explore their sexual feelings. In some settings, many boys search for answers to their questions about sex and the body through watching porn. Whatever your views on it, it’s a really good idea to get well-informed about porn through our page on sex, the internet and technology.
Leave your feedback about this page
We are unable to respond to any personal questions, or offer advice or information in relation to personal matters.