Development of a Zygote

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Development of a Zygote

Many of us know that a baby comes from the mother's womb. But, do we know where that baby comes from? It all begins with a zygote! In prenatal development, there are 3 stages: geminal, embryonic, fetal. We will focus specifically on the germinal stage, which is how the zygote develops. This consists of the first 2 weeks of pregnancy (Iowa State University Digital Press).


Before a zygote is formed, there must be an ovum or an egg cell (Biology Online). Ovulation, occurring once a month, is a process where the ovary releases an egg into the fallopian tube. If fertilization occurs, then the egg will move onto the next steps of pregnancy (Iowa State University Digital Press). If no fertilization occurs, then menstruation occurs. Also known as menstrual period, it is the process in which the uterus sheds its blood lining when pregnancy does not occur (MedlinePlus).


So how are zygotes formed? Zygotes are formed when a sperm and egg meet together, and fertilize (Biology Online). Specifically, the sperm cells penetrate the outer shell of the egg, forming a single-celled zygote. In general, this process is called fertilization or conception (Cleveland Clinic).

Zygote Growth

The zygote will go through mitosis forming a group of cells together called a blastocyst (Cleveland Clinic). Mitosis means that the cells divide, making it grow. As the blastocyst grows, it travels down the fallopian tube into the uterus (Iowa State University Digital Press).

Zygote to Embryonic Stage

Once the blastocyst implants itself on the uterus, it is now an embryo. This occurs at about week 3 of prenatal development (Iowa State University Digital Press).

Embryo to Fetus to Birth

The embryo will continue to grow through cell differentiation, where structures will develop into different organs and parts of the body. At week 9 of prenatal development, the fetal stage begins and the fetus will continue developing its essential body systems until it is fully developed around week 40 (Iowa State University Digital Press).

Zygote to Baby!

Now we know that babies begin from the formation of a zygote. How amazing the human body is!

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