For others, like eye color ... This miniature human was called a homonculus, and scientists thought it was fully pre-formed inside either a sperm cell or an egg cell, and needed just a womb ...

It began with a sperm, the smallest cell in the human body, fusing with the biggest cell… an egg. Every day ... and into mitochondria. The human eye. videoThe human eye This short film offers ...

Although cells can be quite large — consider a frog's egg, for example — most are too small to see with the naked eye. Indeed ... For instance, a single human nerve cell can be over one ...