Fertilization and implantation (2)
zygote; The fertilized egg cell
morula; consists of 16 to 32 stem cells
blastula; a cavity filled with fluid forms within the cluster of cells. Part of the cluster of cells forms the beginning of the actual embryo: the embryoblast or inner cell mass. The outer layer of cells, the trophoblast, protects the embryoblast. The trophoblast also ensures implantation in the uterine lining and later forms the placenta. The trophoblast begins producing HCG
gastrula; In the embryo, which is now a gastrula, cells differentiate and the beginning of the digestive tract is formed.
neurula; the development of the nervous system begins