Small nuclear organelles (0.1–2.0 μM in diameter), present in all eukaryotic cells, involved in a number of different nuclear functions.
The nucleus of eukaryotic cells contains a number of different highly specialized organelles. Unlike cytoplasmic organelles these nuclear structures are not delimited by a membrane but are by all means compartments that contain a number of specific proteins. Most of the organelles can be clearly identified through immunostaining using antibodies directed against specific marker proteins; however, it should be kept in mind that these organelles are highly dynamic structures that often exchange components and therefore many proteins can be found in more than one organelle.
Among these organelles are Cajal bodies (CBs), described over a century ago by Ramon y Cajal. CBs were originally described in neuronal cells but have since been described in a variety of cell types, both in animals and in plants,...