Page 230 - (DK) Help Your Kids with Growing Up: A No-Nonsense Guide to Puberty and Adolescence

228 SEX

Sexual reproduction SEE ALSO
‹
224–225 Sex
Safer sex 230–231 ›
The changes that happen to young people during puberty Pregnancy 238–239 ›
prepare their bodies to be capable of sexual reproduction Pregnancy choices 240–241 ›
when they are older.

What is sexual reproduction?
Sexual reproduction is the result of the fusion
of two germ cells, the female egg and the
male sperm, to produce an embryo. During
sex, sperm is ejaculated out of a male’s penis
into a female’s vagina, and travels up through
the uterus. Although most males produce
millions of sperm, just one is needed to fertilize
the egg. The fused egg and sperm then start
to divide and grow into a cluster of cells. Within
3–4 days, these cells leave the fallopian tube, △ Sperm △ Egg
This is the female germ cell.
This is the male germ cell.
enter the uterus, and attach to the lining of the During orgasm, up to 250 million On average, one of the two ovaries
uterus, where they develop into an embryo. sperm can be ejaculated from the releases an egg every 28 days.
penis into the vagina in a fluid This is known as ovulation.
called semen.
▽ Fertilization
Fertilization can happen if vaginal
sex occurs, without contraception,
when the female has released an egg.
Fallopian tube
An egg travels down the fallopian
Only some sperm tube where it may meet sperm.
make it all the
Uterus way to the egg.
1. One sperm pushes through
the outer layer of the egg.

Sperm Ovary
Sperm swim up This is where
through the an egg is
uterus and into released from. 2. The outer layer
the fallopian tube. hardens to stop other
sperm from entering.

The male ejaculates
semen containing
sperm into the vagina.
3. This is the egg nucleus. The sperm will
fuse with the nucleus. Together they then
Vagina develop into a new cluster of cells.

228-229_299754_HYKWGU_Sexual_reproduction.indd 228 24/03/2017 17:20