Figure 1. Microtubules from mitotic PtK1 cells.
A. Average of 15 consecutive tomographic slices, total thickness ~30 nm, analogous to a conventional thin section. Chromosome (C) and kinetochore (K) show characteristic staining. MTs were identified as KMTs when they ended in a cluster near a chromosome. Bar = 0.1μm.
B. KMTs from the same cell but seen in a ~2 nm slice cut parallel to their axes with the “Slicer” feature of IMOD. Arrow identifies a bending PF; arrowhead indicates a fibril that runs from a PF to the chromatin. Bar = 0.05μm.
C. Multiple image planes that contain the MT axis but are oriented at the angles stated relative to the plane of section; PFs in each view differ in length and extent of flare. Bar = 0.05μm.
D. Stereo pair of a 3D model of all the PFs traced on the MT shown in Fig 1C. Use wall-eyed viewing.
E. Gallery of different KMT ends from the same cell. PF flare is variable; fibrillar material is associated with some PFs (arrows). Bar = 0.05μm.
F. Gallery of non-KMT ends from the polar region of a metaphase spindle; no chromosomes are near. Some MT ends are flared, others not; fibrils are not seen. Bar = 0.05μm.