Figure 3.

Serial section electron microscopic analysis of the congressing chromosome from Fig. 2 to determine kMt numbers and distance from spindle poles. (a) An electron micrograph from a serial section series through the cell. White arrow indicates the AP-moving kinetochore of the congressing chromosome. (b) Measurement of the distances between sister kinetochores and their associated spindle poles. The congressing chromosome was reconstructed in 3D from serial sections, as described in the text. Sister kinetochores are indicated by the light regions at the site where K-fibers (white tubes) attach to the chromosome (gray). The centrioles are schematically represented by cylinders. Distances between kinetochores and the spindle poles were determined by measuring the K-fiber length in 3D. Bar, 2 μm.