Fertilisation occurs when a sperm enters an egg in the fallopian tubes. Millions of sperm are released and swim through the uterus and fallopian tubes to meet a single egg, with only one sperm penetrating the egg's membrane to fuse with the egg nucleus. The nuclei of the sperm and egg then fuse, initiating rapid cell division and replication to form a zygote, which is the fertilized egg.

1. Fertilisation
Target:
• Know where fertilisation occurs in humans

2. Fertilisation and Implantation

3. Millions of
sperm and a
single egg are
released

4. Many sperm will
swim through the
womb and up the
fallopian tubes to
meet the egg…
…but only one will
be able to burrow
through the cell
membrane and fuse
with the egg

5. As the nuclei of the
two gametes fuse
there is a period of
rapid cell division
and replication until
a zygote is formed.

6. The story of fertilisation
• Ollie the Ovum
• Sidney the Sperm
• Fertilisation = when the sperm has entered the
egg
• Zygote = the name for the fertilised egg
• Embryo = when the zygote begins to divide
• Foetus = when the embryo is implanted into the
uterus wall
• Implantation = when the ball of cells implants
itself into the uterus wall and the placenta begins
to grow
Core Science 1 Questions: Pages 62 and 63

7. The story of fertilisation
• Ollie the Ovum
• Sidney the Sperm
• Fertilisation = when the sperm has entered the
egg
• Zygote = the name for the fertilised egg
• Embryo = when the zygote begins to divide
• Foetus = when the embryo is implanted into the
uterus wall
• Implantation = when the ball of cells implants
itself into the uterus wall and the placenta begins
to grow
Core Science 1 Questions: Pages 62 and 63