The homing cursor: A tool for three‐dimensional chromosome analysis

When studying the three‐dimensional shape of prophase chromosomes (or any other tubular structure), it is useful to represent these structures as a string of three‐dimensional Cartesian coordinates along the medial axis. This procedure was automated in order to limit the number of human interactions and to improve reproducibility. In this paper the design, implementation, and validation of the automated method is presented. From the data presented it can be concluded that the cursor algorithm provides an objective and therefore reproducible method to trace the medial axes of prophase chromosomes automatically. This method could allow a more extensive understanding of the (changes in) chromosome organisation throughout the cell cycle, its relation to cell function, and the complex process of chromosome condensation. © 1993 Wiley‐Liss, Inc.