Reproduction in Humans – Fertilisation

Millions of sperm cells are released and travel to the female reproductive system where fertilisation takes place. However, only the strongest sperm cell will fertilise the egg. The fertilised egg is known as a zygote. As the fertilised egg divides to become a ball of cells, it is known as a blastocyst.

Move the scroll bar below the image to the right gradually to compare the sizes of the human egg cell (biggest cell in the human body) and sperm cell with small objects all around us like a grain of rice and a grain of salt!