Morphogenic matrix

The morphogenic matrix is the structure of the Changelings which enables them to change their shape.

The morphogenic virus which Section 31 infected the Great Link made a Changelings' morphogenic matrix unstable and often led to them being unable to hold humanoid forms. 

In 2373, the infant Changeling that Quark gave to Odo had had its morphogenic matrix damaged by exposure to tetryon radiation from the Badlands artificial quantum singularity. It died several weeks later, but gave Odo back his Changeling abilities. 

In 2375, Julian Bashir scanned a sample given by Odo to see if by studying his morphogenic matrix he could synthesize organic tissue that can change forms. 

After Bashir cured Odo of the Changeling disease, Odo's morphogenic virus needed time to heal. 

Several days later, the crew of the USS Defiant (NX-74205) (II) were unable to transport the Female Changeling aboard from Dominion Headquarters on Cardassia as her morphogenic matrix had become too unstable.