TABLE 1:

Structure data obtained.

Species and number of cells examined	Number of 250–300-nm ­sections reconstructed	Dimensions of volume imaged	Approximate fraction of spindle reconstructed
Chlamydomonas
Three metaphases	Four sections ( Figures 2 and 3)	2.5 × 4.3 × 1.0 µm3	One-quarter
	Four sections ( Figure 4)	2.4 × 4.7 × 1.0 µm3	One-quarter
	Six sections (Supplemental Figure S1)	2.6 × 5.2 × 1.5 µm3	One-quarter
RPE1
Two metaphases	Five sections ( Figures 5 and 6)	6.6 × 6.6 × 1.5 µm3	One-fifth
	Four sections (Supplemental Figure S2)	5.5 × 11.0 × 1.0 µm3	One-fifth
PtK
One metaphase	Six sections ( Figures 7 and 8)	13.4 × 13.1 × 1.8 µm3	One-quarter

Section thickness was estimated at the time of microtomy. This value multiplied times the number of sections gave the thickness of the reconstruction. Areas imaged were determined from the numbers and sizes of pixels.