APPLICATION OF CONFOCAL LASER MICROSCOPY AND 3-DIMENSIONAL VORONOI DIAGRAMS FOR VOLUME AND SURFACE ESTIMATES OF INTERPHASE CHROMOSOMES

This study demonstrates the use of Voronoi tessellation procedures to obtain quantitative morphological data for chromosome territories in t he cell nucleus, As a model system, chromosomes 7 and X were visualize d in human female amniotic fluid cell nuclei by chromosomal in situ su ppression hybridization with chromosome-specific composite probes. Lig ht optical serial sections of 18 nuclei were obtained with a confocal scanning laser fluorescence microscope. A three-dimensional (3-D) tess ellation of the image volumes defined by the stack of serial sections was then performed, For this purpose a Voronoi diagram, which consists of convex polyhedra structured in a graph environment, was built for each nucleus. The chromosome territories were extracted by applying th e Delaunay graph, the dual of the Voronoi diagram, which describes the neighbourhood in the Voronoi diagram. The chromosome territories were then described by three morphological parameters, i.e, volume, surfac e area and a roundness factor (shape factor), The complete evaluation of a nucleus including the calculation of the Voronoi diagram, 3-D vis ualization of extracted territories using computer graphic methods and parameterization was carried out on a Silicon Graphics workstation an d was generally completed within 5 min, The geometric information obta ined by this procedure revealed that both X- and 7-chromosome territor ies were similar in volume, Roundness factors indicated a pronounced v ariability in interphase shape for both pairs of chromosomes, Surface estimates showed a significant difference between the two X-territorie s but not between chromosome 7-territories.