Source:http://linkedlifedata.com/resource/umls/id/C0035695
MSH: Nuclear nonribosomal RNA larger than about 1000 nucleotides, the mass of which is rapidly synthesized and degraded within the cell nucleus. Some heterogeneous nuclear RNA may be a precursor to mRNA. However, the great bulk of total hnRNA hybridizes with nuclear DNA rather than with mRNA.,CSP: nuclear nonribosomal RNA larger than about 1000 nucleotides, the mass of which is rapidly synthesized and degraded within the cell nucleus; some heterogeneous nuclear RNA may be a precursor to mRNA, however, the great bulk of total hnRNA hybridizes with nuclear DNA rather than with mRNA.,NCI: The name originally given to large RNA molecules found in the nucleus, which are now known to be unedited messenger RNA transcripts, or pre-mRNAs. (BioTech Life Science Dictionary)