Fig. 4.

Invaginations of the nuclear envelope in mitotic prophase. C2C12 cells are immunostained with antibodies against lamin B (green), and the DNA is counterstained with DAPI (magenta). (A) Maximum intensity projections, (B) lateral, and (C) orthogonal cross sections. Scale bars, 5 µm. Inset boxes are shown below at 4× magnification (scale bars, 1 µm). 3D-SIM reveals the globular substructure of condensed chromosomes and the fine-structured fibrillar network of the nuclear lamina (movie S2). (D) Lateral and axial line profiles of dashed lines in (B) and (C), respectively. Whereas the lateral peak widths are only slightly decreased in the lateral direction (1 versus 1′), the axial profiles show clearly decreased peak widths after deconvolution, indicating a substantial improvement of axial resolution (2 versus 2′). With 3D-SIM, the peak widths of the lamin B signal are about halved with respect to the deconvolved confocal image in lateral and axial directions, and double peaks are resolved where only single peaks are seen in the confocal profiles. Similarly, DAPI staining shows multiple small peaks, which again reflects the increase of image details in 3D-SIM.