ABSTRACT

The isolation and characterization of the nuclear ground substance or nuclear matrix has provided a new stimulus for investigating the relationships of nuclear form and function in the eukaryotic cell. The nuclear matrix is currently an exploding area of research and investigators are exploiting the matrix for studying nuclear functions. The model of the interphase nucleus as a bag of chromatin immersed or embedded within a homogeneous, unstructured nucleoplasm was radically changed with the application of electron microscopy to the cell nucleus. It is important to recall that the interchromatinic regions of the nucleus contain, aside from the nonchromatin matrix material, diffuse chromatin. Associated with increases in nuclear size is a decrease in the relative volume occupied by the condensed chromatin and a corresponding increase in the in situ matrix. In addition to size changes, treatment of cells with drugs which inhibit various biosynthetic processes often lead to striking perturbations in nuclear shape and internal morphology.