We are investigating the structure and function of chromosomes during meiosis, when chromosomes are recombined, shuffled, and reduced to the haploid state (during production of sperm or eggs). High-resolution deconvolution microscopy is used to collect multi-wavelength three-dimensional optical reconstructions of whole nuclei in meiotic cells of higher plants. Specific DNA sequences are localized within the nucleus by fluorescence in situ hybridization (FISH), and sophisticated software is used to analyze the resulting spatial and quantitative image data. Having adapted novel techniques for 3D FISH with plant meiotic chromosomes (Bass et al., 1997), we are now working on two related projects, the analysis of meiotic telomere behavior and the development of a new cytogenetic map of maize chromosome 9.