Fig. 3. feSEM and TEM of lamin LIII-induced intranuclear membrane arrays. FLAG-tagged lamin LIII was expressed by nuclear injection of plasmid DNA. (A) Nuclear envelope of an oocyte overexpressing lamin LIII, shown at low magnification. Lamin-induced intranuclear membrane arrays (arrows) are distributed throughout the nuclear envelope. (B) Lamin LIII-induced membrane arrays sparsely covered by lamin filaments. Arrows mark filament-free areas of the extra membrane. (C-E) Lamin LIII-induced membrane arrays densely packed with filaments. Nuclear envelopes were either (C) fixed immediately or (D,E) treated with 0.5% Triton X-100 before fixation to remove membranes. In several areas of the membrane arrays, the LIII filaments are organized in a lattice-like arrangement. Note the pronounced repeat pattern along the LIII filament axis in D. The inset in D shows repeats at higher magnification. The line of arrowheads in the inset highlights the repeats. (F) TEM section of an isolated oocyte nucleus expressing lamin LIII. (G,H) Immuno-feSEM detection of FLAG-tagged lamin LIII on intranuclear membrane arrays using FLAG-specific antibodies. The immuno-gold labels are indicated by gold spots in G and H.