Microtubules are tube-like polymers that play an important role in cell division. They form the spindle, a microtubule assembly that segregates the chromosomes. One important method for investigating microtubules in cells is electron tomography. Thick (300nm) serial sections of cells are prepared for electron microscopy and imaged on a CCD camera. With the use of image processing techniques, we are able to automatically extract the centerlines of microtubules within a section. In this project we will develop methods and software for a quantitative analysis of full mitotic spindles. These methods will allow joining electron tomograms and extracted microtubule centerlines within (in xy) and across (z) physical sections to create a geometric model of the entire spindle, which is then visually and quantitatively analyzed.