What is the Difference Between Blastocyst and Embryo?

The main difference between a blastocyst and an embryo lies in their stages of development and structure. Here are the key differences:

Blastocyst: A blastocyst is a rapidly dividing ball of cells that forms about five to six days after a sperm fertilizes an egg. It consists of an inner group of cells that will become the embryo and an outer group of cells that will nourish and protect it. The blastocyst stage is crucial for in vitro fertilization (IVF) and occurs before the embryo stage.
Embryo: The blastocyst is considered an embryo when the amniotic sac develops, usually around day 10 to 12 after fertilization. The embryo is the early stage of human development in which organs and critical body structures are formed. It develops within the amniotic sac under the lining of the uterus.

In summary, a blastocyst is the early stage of cell division following fertilization, while an embryo is the stage that follows the blastocyst, during which organs and body structures are formed.