Zygote

Definition - What does Zygote mean?

A zygote is the single-cell embryo that is produced when a man's sperm combines with a woman's egg. It is the first cell in the human body.

FertilitySmarts explains Zygote

When a female sex cell, the egg, and a male sex cell, sperm, meet, the sperm may penetrate the egg’s exterior, causing the mixing of the 23 male and 23 female chromosomes. This is considered the moment of conception. The now fertilized egg is considered a zygote.

The zygote is covered in a protective covering known as the the zona pellucida and contains 46 unique chromosomes. Chromosomes contain tightly packed molecules called DNA that contain all of the instructions needed to transform the single cell into an infant.

Zygote development typically occurs in the fallopian tubes, where it completes the first cell division around 24 to 30 hours after fertilization. After around three days of development, the zygote becomes a solid ball of called called the morula. By day four, the morula becomes a blastocyst, the next phase of development.

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