Fertilized human egg (zygote) during first cleavage stage. Egg has split into two cells.

Lateral view of a silhouette of an adult female against a highlighted background.

Human egg seconds after fertilization by a spermatozoon. Male pronucleus not yet formed.

Montage illustration about gene therapy and engineering containing a vitruvian man, male and female symbols, DNA, and sperm fertilizing an egg

sperm and egg

The first of a series of mitotic cell divisions occurring in the ovum immediately following its fertilization.

Fertilized human egg (zygote) having split into four cells.

Montage illustration about in-vitro fertilization containing an egg, a couple, DNA and chromosomes

Side view of a pregnant woman holding her belly

Human egg seconds after having been fertilized by a spermatozoon. Egg is still at single cell stage prior to pronucleate stage and cleavage.

Side view of a pregnant woman resting her hand on her belly

Side view of a young pregnant woman with both hands on her belly

Fertilization