have artists create pictures, buildings,
and statues.
Leonardo da Vinci worked during the
late 1400s and early 1500s. He painted
two of the world’s most famous works:
the Mona Lisa and the Last Supper.
Leonardo also made statues and
designed weapons. He even drew up
plans for a helicopter.
Michelangelo and Raphael were also
important artists of this period. They
painted religious figures but gave them a
realistic, human quality.
Exploration
The Renaissance also led people in
Europe to explore parts of the world
they had never seen. Christopher
Columbus and others from Spain and
Portugal discovered two continents—
North and South America—that had
been unknown to Europeans. This led
to other voyages of discovery.
Late Renaissance
No one event marks the end of the
Renaissance. The spirit of discovery that
defined the period led people to try new
ideas in all areas of life. Slowly artists
turned to new styles. New ways of
thinking about other fields, such as government
and politics, also developed.
#More to explore
Copernicus, Nicolaus • Gutenberg,
Johannes • Leonardo da Vinci • Medici
Family • Michelangelo • Middle Ages
Reproductive
System
All living things reproduce, or create
offspring. Animals’ offspring are often
called babies. The body parts that allow
animals to create babies belong to the
reproductive system.
A painting from the early 1500s
shows the realistic style of art
that was popular during the
Renaissance. It also shows the
type of dress worn by wealthy
ladies in Italy.
46 Reproductive System BRITANNICA STUDENT ENCYCLOPEDIA
Types of Reproduction
Some animals can create offspring
through asexual reproduction. This
means that one animal creates offspring
on its own. For example, corals, hydras,
and sea anemones can reproduce
through a process called budding. In
budding, a growth called a bud breaks
off from the animal to make a new animal.
A few animals, including some
worms, can break in half to create two
separate animals.
Most animals use sexual reproduction
to have babies. This means that two sex
cells, one from a male and one from a
female, join together to create a baby.
In some animals, including many types
of fish, the male and female sex cells
join together in water, outside the
female’s body. In other animals the sex
cells join together inside the female’s
body.
After the sex cells join they grow into a
baby. The babies of some animals, such
as birds and many reptiles, develop in
eggs outside the female’s body. The
babies of most mammals develop inside
the female’s body.
Human Reproduction
Like other mammals, humans reproduce
sexually. A woman’s body supports a
baby as it grows. For these reasons men
and women have different reproductive
organs.
Male Reproductive System
In men the main reproductive organs
are the testes. The two oval-shaped
Men and women have different reproductive
organs. A woman’s ovaries produce
egg cells. A man’s testes produce sperm.
BRITANNICA STUDENT ENCYCLOPEDIA Reproductive System 47
testes sit behind the penis in a pouch
called the scrotum. The testes make the
male sex cells, called sperm. Sperm are
too tiny to see without a microscope.
They are shaped like tadpoles with long
tails. The tail of a sperm is what moves
it forward.
The sperm travel through a tube toward
the penis. They mix with other fluids to
form a liquid called semen. During
sexual intercourse a small amount of
semen passes through the tip of the
penis into the woman’s body. This
semen contains between 200 and 300
million sperm. The sperm then travel
toward the woman’s sex cell, or egg.
Female Reproductive System
In women the main reproductive organs
are the ovaries. The two almond-shaped
ovaries sit inside the lower belly. When a
girl is born her ovaries contain up to
500,000 egg cells. Two tubes, called
fallopian tubes, connect the ovaries to
the uterus. The uterus is a muscular
organ that holds a growing baby.
Beginning when a girl is about 12 years
old, one ovary releases an egg once a
month. This process is called ovulation.
The egg travels from the ovary through
the fallopian tube to the uterus. If the
egg does not meet a sperm cell on its
journey, it dies. The egg and some blood
One of a woman’s ovaries releases an egg each month. If the egg meets a sperm cell, it
may become fertilized. The fertilized egg travels to the uterus, where it grows into a baby.
48 Reproductive System BRITANNICA STUDENT ENCYCLOPEDIA
then pass out of the uterus and through
the vagina, a muscular tube that leads
out of the body.
Fertilization, Pregnancy, and Birth
Sperm enter the woman’s body through
the vagina. The sperm swim up through
the uterus and into the fallopian tubes.
If an egg is in one of the fallopian tubes,
the sperm try to join with it. Only one
sperm can enter, or fertilize, the egg.
The rest of the sperm die.
Once the egg is fertilized, pregnancy (or
gestation) begins. The fertilized egg
moves into the uterus. As it travels it
starts to divide into many more cells.
After about five or six days these cells
burrow into the wall of the uterus.
There the cells begin to develop into a
baby. At first the developing baby is
