An embryo transitions into a fetus at the 8th week of gestation.
An embryo is an organism in the early stages of development that cannot survive on its own. The precise definition varies; in humans, for example, a fertilized egg can be considered an embryo until around the eighth week of pregnancy, at which time it is called a fetus. Embryos in animals typically indicate any stage of prenatal development, including those in uteri or eggs. Plant embryos can take many different forms, although they are commonly encased in seeds.
“Embryo” refers to multicellular organisms or eukaryotes.
The term “embryo” is only used to refer to “eukaryotes” or multicellular organisms. Typically, people use the term specifically to refer to diploid eukaryotes, which have a complete set of genetic material from two donors. This genetic material takes the form of haploid sperm and eggs; a haploid cell contains only half of a set of chromosomes, meaning it cannot develop into anything unless it is combined with another.
The formation of an embryo begins at fertilization.
The formation of an embryo begins at fertilization. When an egg and a sperm meet, they form a “zygote”. A zygote is a single diploid cell, created by the fusion of two haploid cells. After fertilization, the zygote begins to divide, laying the foundation for the mature organism that will eventually be born, incubate, or grow. When this division begins, the zygotes develop into embryos.
An embryo develops into a blastocyst in 5 stages.
The status of embryos in humans is quite complex. At conception, the human egg and sperm become a zygote, which begins to divide, becoming an embryo. There is much debate about defining human embryos in terms of “life”. This debate has generated conflict in many parts of the world, especially when it comes to terminating a pregnancy. As a human embryo matures, it begins to morph into a recognizable form, at which point people refer to it as a fetus.
Development in Animals
A few days after conception, the embryo reaches the uterus, where it implants in the lining of the uterus.
Embryos cannot survive independently because they do not have the tissues, body structure and organs necessary to do so. The father of an embryo must feed and care for it until it reaches viability. In mammals, this is done by incubating it inside the body and nourishing it with nutrients from the parents. Animals that lay eggs provide the embryo with a rich layer of nutrients encased in a hard shell, which protects it until it is ready to hatch.
At the time of conception in humans, the egg and sperm become a zygote which begins to divide, becoming an embryo.
The development of embryos in plants depends on how different species replicate. Those that use seeds include small structures that develop into leaves, roots and stems, which constitute the embryos of these plants. Other species produce embryos as tiny plants that grow along the larger plant before separating on their own to continue growing.