During development of the embryo it goes from being a single cell, the fertilized egg, to being a multi-cellular organism with billions of cells in it.

胚胎的发育,始于一个单一细胞,即受精卵,直到形成一个以十亿计数量的细胞构成的,多细胞有机体

耶鲁公开课 - 生物医学工程探索课程节选

This one cell, this one fertilized cell which is unique because it's the - its chromosome contains the combination of the sperm and the egg, develops into an embryo and then on birth develops into a human.

这个受精卵,是独一无二的,因为它的染色体,包含了精子和卵子的组合,并由此发育成为一个胚胎,之后形成一个人类个体

耶鲁公开课 - 生物医学工程探索课程节选