Spindles are the structures at the heart of cell division that are responsible for segregating chromosomes. Division must occur without introducing errors in the chromosomes. Spindles in all organisms are made up of long polymers called microtubules. Needleman and Mazur used laser ablation to obtain highly detailed data on microtubules in large spindles, providing extensive information on how these structures function. By analyzing the recovery after the laser cutting they were able to develop a new model to describe the properties of the microtubules in the spindle.