“When cell nuclei (or cells) are extracted in certain ways, an extensive array of filaments is observed in the remnant nucleus: “the nuclear matrix.” Onto this framework virtually every step in gene readout has been conceptually draped. Some investigators worshipfully attribute to this envisioned nuclear scaffold the same biochemically enabling attributes that the cytoskeleton (demonstrably) conveys for cell shape, cell locomotion, intracellular vesicular traffic, and chromosome movement during cell division. But many other investigators consider this nuclear matrix fraction to be a global aggregation phenomenon. Few aspects of contemporary eukaryotic cell biology have been more contentious.”
Source: Half a Century of “The Nuclear Matrix” Mol Biol Cell. 2000 Mar; 11(3): 799–805.
It's also been termed the “nuclear-scaffold” or “NuMat”. The exact function of the matrix (if it exists) is disputed. (see link above).