Objective: to extract a model of the three dimensional relationships from a series of sections.

From a series of sections will come a series of images of the target structure. Our example here is the flagellar apparatus of the flagellate, Percolomonas cosmopolitus. The information from contiguous sections (slices) is stacked into a series representing the sections through the material, and positional information tracked through the stack.

There are a variety of software packages out there that will help to develop a reconstruction of the flagellar aparatus, or check out .

However, the simplest way to build the reconstruction is to print or display the images with the same magnification, and trace the relevant structures onto transparent sheets using color-coding for each element. You can use perspex (to mimic the thickness of the sections) or transparencies for overhead projectors, and simply lay these on top of one another. These can also be read into appropriate software to rebuild three dimensions and create an image that can be manipulated.

During this process, the orientation of the basal body (bodies) is established.

To the right are a micrograph and an associated sketch from the flagellate Percolomonas cosmopolitus. The sketches can be stacked together, and these provide a much better sense of the three-dimensional relationships of components.

Powerpoint display of a stack of images.

The analysis is interactive - inasmuch as a study of the sketches should direct attention back to the original micrographs or indeed back to the electron microscope. The process continues until all uncertainty is eliminated.

In this process, sections may be compressed or twisted as they are sectioned, so the positional relationships among elements may move a little. It is also possible to rotate sections and tilt them in the electron beam so that a series of sections is oriented to the axis of one element, such as the mature basal body.

The structure is then drawn.

End

Image and copyright D J Patterson

Image and copyright D J Patterson