Inner cell mass

Definition

The inner cell mass is a group of cells inside the blastocyst during early embryonic development from which the embryo and subsequently the fetus will develop. It differentiates into the embryoblast, which gives rise to all the tissues and organs of the organism.

Related terms

Blastocyst:

A structure formed in early development in mammals after fertilization, consisting of an outer layer called the trophoblast that surrounds a fluid-filled cavity and the inner cell mass.

Embryoblast: The part of the inner cell mass in a mammalian blastocyst that develops into the definitive structures of the fetus.

Differentiation:

The process by which cells or parts of an organism change during development to serve specific functions, such as cells from ICM specializing into heart, brain, or lung cells