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Immunofluorescent image of antibodies to Sm
Antibodies to Sm reacting with splicesomes (snurp particles) in the nucleus in a "speckled" pattern. These particles are the sites of precursor mRNA splicing. The snurp particles are distributed in the nucleoplasm but not in the nucleoli. A cell in mitosis does not show assembly of Sm antigen into particles but Sm antigen is more diffusely distributed in the nucleoplasm outside the mitotic plate region.