An embryo is an animal or a plant in its earliest stage of development.
The embryo of vertebrates is defined as the stages between the first division of the fertilized egg to the birth or hatching.
An embryo is called a fetus at a more advanced stage of development and up until birth. In humans, this is from the eighth week after fertilization onward.
The embryo of invertebrate animals is usually called a larva.
In plants, the embryo is part of the seed, consisting of root, shoot, and cotyledons.
- See also : In Vitro Fertilization -- embryology
