A possible association of nuclear lamina with chromatin

The nuclear lamina associated with chromatin was examined by electron microscopy. Nuclei isolated from rat ascites hepatoma cells were swollen in 0.2 mM EDTA (pH 7.0) and broken by a homogenizer. The resulting nuclear fragments were dialyzed against 0.2 mM EDTA (pH 7.0) overnight, fixed in formalin and sedimented on grids by centrifugation, then stained with 2% uranyl acetate and rotary-shadowed with platinum-palladium. The nuclear lamina consists of two filaments, twisting together both the filaments associated with chromatin fiber. The single filament of nuclear lamina of about 31 nm in width forms certain rings of about 187 nm in diameter, taking a distance of about 0.37 micron in length between the neighbouring rings. Thus, the arrangement of rings was proposed a packing structure in conforming the nuclear laminar complex with chromatin.