Identity and Personality

Prenatal Development

1. Prenatal development is the process in which a human embryo or fetus gestates during pregnancy, from fertilization until birth.
2. The blastocyst is a structure formed in the early development. It possesses an inner cell mass which subsequently forms the embryo. The outer layer consists of cells collectively called the trophoblast which becomes the placenta.




Blastocyst just before implantation.



3. In humans, an embryo is a prenatal human generally considered to be between the first and the eighth week of development after fertilization and from then it is instead called a fetus.
4. A fetus is a prenatal human between its embryonic state and its birth.
5. Teratology is the study of abnormalities of physiological development.