It begins at puberty.
With a sperm cell and a egg cell.
Life begins when the egg cell and sperm cell unite to form the zygote.
When an egg was fertilized by a sperm cell.
A sperm and an egg.
the egg is larger than the sperm cell
The uniting is known as fertilisation of the egg by the sperm.
egg by far
Twenty-three chromosomes are in a cell that is formed from a sperm and egg cell.
FERTILIZATION
Egg cells are the biggest: you could only fit one on the head of a pin. But I'm not sure if a sperm cell is bigger than a red blood cell or vice versa.
A sperm fused with an egg
A sperm cell is used to fertilize an egg from a female. The combination of the sperm and the egg produces a fertilized egg which will become a new individual.