Animals
In animal development, the term zygote is also used more loosely to refer to the group of cells formed by the first few cell divisions, although this is properly referred to as a morula.
In mammalian reproduction, after fertilization has taken place the zygote travels down the fallopian tube, while dividing to form more cells without the zygote actually increasing in size. This cell division is mitotic, and is known as cleavage. All mammals go through the zygote stage of life. Mammalian zygotes eventually develop into a blastocyst, after which they are more generally termed an embryo, and then a fetus.
A human zygote exists for about four days, and becomes a blastocyst on the fifth day.
Read more about this topic: Zygote
Famous quotes containing the word animals:
“Lions, wolves, and vultures don’t live together in herds, droves or flocks. Of all animals of prey, man is the only sociable one. Every one of us preys upon his neighbour, and yet we herd together.”
—John Gay (1685–1732)
“The moles nested in my cellar, nibbling every third potato, and making a snug bed even there of some hair left after plastering and of brown paper; for even the wildest animals love comfort and warmth as well as man, and they survive the winter only because they are so careful to secure them.”
—Henry David Thoreau (1817–1862)
“Why do precisely these objects which we behold make a world? Why has man just these species of animals for his neighbors; as if nothing but a mouse could have filled this crevice?”
—Henry David Thoreau (1817–1862)