a blastocyst is the stage of embryonic development that consists of
Blastocyst The blastocyst is a structure formed in the early development of mammals. It possesses an inner cell mass (ICM) which subsequently forms the embryo. The outer layer of the blastocyst consists of cells collectively called the trophoblast. This layer surrounds the inner cell mass and a fluid-filled cavity known as the blastocoele. The trophoblast gives rise to the placenta. The name "blastocyst" arises from the Greek βλαστός blastos ("a sprout") and κύστις kystis ("bladder, capsule").
Gestation In humans, birth normally occurs at a gestational age of about 40 weeks, though it is common for births to occur from 37 to 42 weeks.[1] After 8 weeks, the embryo is called a fetus.
Human embryogenesis The germinal stage refers to the time from fertilization through the development of the early embryo until implantation is completed in the uterus. The germinal stage takes around 10 days.[2] During this stage, the zygote begins to divide, in a process called cleavage. A blastocyst is then formed and implanted in the uterus. Embryogenesis continues with the next stage of gastrulation, when the three germ layers of the embryo form in a process called histogenesis, and the processes of neurulation and organogenesis follow.
Egg Reproductive structures similar to the egg in other kingdoms are termed "spores," or in spermatophytes "seeds," or in gametophytes "egg cells".