PUBERTY: MAKING BABIES

In order to make a baby, two things are needed: an ovum from a woman’s body and a sperm from a man’s body. You may have heard adults talking about an ovum and calling it ‘a woman’s egg’ or talking about a sperm and calling it ‘a man’s seed’. When many of the boys and girls in our classes hear the word ‘egg’ they think about the kind of eggs that chickens lay and that we eat at breakfast. When they hear the word ‘seed’, they think about the things we plant in the ground in order to grow flowers or vegetables. But the ovum and the sperm are not like these kinds of eggs and seeds. For one thing, an ovum is much smaller than the eggs we cook – in fact, it is much smaller than the smallest dot you could make with the tip of even the sharpest pencil point. And a sperm is even smaller than an ovum.

Perhaps the best way to think of a sperm and an ovum is to think of each of them as being half of a seed. When these two halves of a seed come together, a human baby begins to grow.

Sperm are made in the testicles, the two egg-shaped organs inside the scrotum. Sometimes when a man and a woman are having sexual intercourse and the man’s penis is inside the woman’s vagina, the man ejaculates. When a man ejaculates, the muscles of the penis contract and the sperm are pumped out of the testicles, through the urethra, a hollow tube in the centre of the penis, and out through the opening in the centre of the glans, as shown in Illustration 5. A few spoonfuls of a creamy fluid, full of millions of tiny, microscopic sperm, come out of the penis. This liquid is called ejaculate, or in slang terms ‘come’.

After the sperm leave the penis, they start swimming up towards the top of the vagina. They pass through a tiny opening at the top of the vagina that leads into an organ called the uterus. The uterus is a hollow organ, and in a grown woman it is only about the size of a clenched fist. But the thick muscular walls of the uterus are quite elastic and, like a balloon, the uterus can expand to many times its size. The uterus has to be able to expand like this because it is here, inside a woman’s uterus, that a baby grows.

Some of the sperm swim up to the top of the uterus and into one of two little tubes or tunnels called the Fallopian tubes. Not all the sperm make it this far. Some drift back down to the uterus and out into the vagina, where they join other sperm that never made it out of the vagina.

These sperm and the rest of the creamy, white liquid dribble back down the vagina and out of the woman’s body.

If you cut an apple in half, you would be able to see the seeds and core on the inside of the apple. This drawing, which shows the inside of an apple, is called a cross-section.

Sperm are made in the testicles. When a man ejaculates, the sperm travel through the urethra, a hollow tube in the centre of the penis, and spurt out from an opening in the glans.

Women, too, make seeds in their bodies. When we are talking about just one of these seeds, we use the word ovum. When we are talking about more than one, we use the word ova. The ova ripen inside two little organs called ovaries. In a grown woman the ovaries produce a ripe seed about once a month. When this seed is ripe, it leaves the ovary and travels down the Fallopian tube towards the uterus. If a woman and a man have sexual intercourse around the time of the month when the ripe ovum has just left the ovary, there’s a good chance that the sperm and ovum will meet inside the Fallopian tube. When a sperm and ovum meet, the sperm penetrates the outer shell of the ovum and moves inside it. This joining together of the ovum and the sperm is called fertilization, and when a sperm has penetrated an ovum, we say that the ovum has been fertilized.

Most of the time the ovum travels through the Fallopian tube without meeting a sperm, and the tiny ovum just disintegrates. But if the ovum has been fertilized, it doesn’t disintegrate. Instead, the fertilized ovum plants itself on one of the inside walls of the uterus and over the next nine months it grows into a baby. When a woman is ready to have a baby, her uterus opens up and her vagina expands so that the baby can move from the uterus, through the vagina and out into the world.

During puberty girls make their first ripe ova and boys begin making sperm in their testicles. Girls begin to develop breasts, to grow hair in new places on their bodies and to go through other important changes on the inside and outside of their bodies. As we said at the beginning of this chapter, boys’ bodies also change, both on the inside and on the outside, as they go through puberty. In the following chapters we will talk about the changes that take place in a boy’s body during puberty. (We have also included a chapter on the changes that a girl goes through during puberty, because most boys are curious about girls.) If you’re like the boys and girls in our classes, you probably will have a lot of questions about these things.

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