The key difference between a zygote and an embryo lies in their developmental stages and cellular complexity:
- Zygote : The zygote is the very first stage of a new organism's life, formed immediately after fertilization when a sperm cell fuses with an egg cell. It is a single diploid cell containing 46 chromosomes (23 from each parent) and represents the initial cell from which the organism develops
. The zygote undergoes rapid mitotic divisions but remains a single cell initially.
- Embryo : The embryo stage follows the zygote stage. It is multicellular, formed after the zygote undergoes several rounds of cell division and differentiation. The embryo grows rapidly, with cells beginning to specialize and form the foundations of major organs and body systems. This stage lasts from about day 2-3 post-fertilization until the end of the eighth week of pregnancy
In summary:
Feature| Zygote| Embryo
---|---|---
Stage| First stage post-fertilization| Second stage, after zygote divides
Cell number| Single cell| Multicellular
Duration| About 24-36 hours| From day 2-3 to 8 weeks post-fertilization
Developmental process| Rapid mitotic division begins| Cell differentiation and
organ formation
Location| Fallopian tube| Uterus
Thus, the zygote is the initial fertilized cell, while the embryo is the developing multicellular organism formed from the zygote's divisions and differentiation
