Summary
The early developmental stage of an organism produced by division of the zygote.
In depth
In humans, the term embryo applies from about two weeks until the end of week eight, a period of rapid organ formation, followed by the fetal stage. The embryo is most vulnerable to teratogens during organogenesis.
Embryonic development includes cell division, differentiation, morphogenesis and growth. Tissue folding and cell movement shape organs. Embryos of different vertebrates look similar at the phylotypic stage.
Example: von Baer noted that early embryos of fish, birds and mammals resemble each other.
An embryo is the early stage of a multicellular organism, from the first divisions of the zygote until organs begin to form. In humans, the term covers roughly the first eight weeks after fertilisation, after which it is called a fetus.
Key events are cleavage, blastulation, gastrulation, neurulation and organogenesis. Embryos may develop in an egg with yolk, as in birds and reptiles, or inside the mother with a placenta, as in most mammals. Embryonic stages across vertebrates look similar early on, reflecting shared ancestry.
Example: chick embryos are widely used because they can be watched through a window in the shell.
Frequently asked questions
What is Embryo?
The early developmental stage of an organism produced by division of the zygote.
Which area of biology covers Embryo, and how advanced is it?
Embryo is one of the 54 topics in Developmental Biology. It is rated Beginner, so it suits learners who are starting out in biology. Related topics in this area include Fetal Development, Organogenesis, Zygote.
Why does Embryo matter?
Errors at this stage cause many miscarriages and birth defects.
Can you give an example of Embryo?
The heart starts beating around week 5.
What should I learn before Embryo?
Embryo is a Beginner topic, so no earlier topic is required. Other Beginner topics in Developmental Biology that pair well with it include Fertilisation, Zygote, Cleavage.
What topics are related to Embryo?
The closest topics to Embryo are Fetal Development, Organogenesis, Zygote, Model Organisms in Development. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Embryo?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Embryo. To practise the whole of Developmental Biology, use the Developmental Biology quiz.
How is Embryo different from Fetal Development?
Embryo: The early developmental stage of an organism produced by division of the zygote. Fetal Development: In humans the embryo becomes a fetus after eight weeks, growing until birth around nine months. Read both side by side and note what each one explains.
How should I study Embryo step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Fetal Development and explain the difference aloud. Finally, take the Developmental Biology quiz and come back to this page for any question you miss.