Cajal bodies ( called Cajal bodies, CBs ) was first described 100 years ago in mammalian neurons . It is now known that CB are highly conserved structures present in the somatic and germ cells of plants and animals. CB marker protein coilin , a phosphoprotein probably responsible for location of numerous macromolecules in Cajal bodies . The presence of small nuclear RNA ( snRNA ) in the CB indicates the participation of this structure in the spatial organization of the elements involved in the submission of pre- mRNA splicing .