Volume ratios of painted chromosome territories 5, 7 and X in female human cell nuclei studied with confocal laser microscopy and the Cavalieri estimator

Three-dimensional reconstruction of painted human interphase chromosomes: active and inactive X chromosome territories have similar volumes but differ in shape and surface structure.

“…Estimates for territory volumes and surface areas typically varied ± 30% throughout the entire threshold range, while the variation of the ratios of these morphological parameters for homologous territories was <10%, indicating that ratios are better suited to judge volume and surface area differences between painted chromosome territories. Similar volume ratios were obtained for cells fixed with either 4% buffered formaldehyde or with methanol/acetic acid (3:1, vol/vol) (Rinke et al, 1995). This indicates that volume ratio measurements are relatively robust even against the shrinkage effects induced by the latter type of fixation.…”

“…Recently, we and others (Ikizyan et al, 1994) have combined light optical serial sectioning of painted human chromosome territories and 3D image analysis procedures to estimate territory volumes in various human cell types. In contrast to our expectation, we obtained similar volumes for' both X territories in female cell nuclei (Bischoff et al, 1993;Eils et al, 1995a;Rinke et al, 1995). Here, we describe the results of a more detailed study of 3D-morphology differences between Xi and Xa territories in three-dimensionally preserved female human amniotic fluid cell nuclei.…”

“…In all aspects studied so far, the 3D morphology of Xa territories was more similar to chromosome 7 territories than to Xi territories. This conclusion was confirmed when volume, surface area, and shape parameters of chromosome X and chromosome 7 territories were measured using the classical Cavalieri approach (Rinke et al, 1995) instead of the Voronoi tessellation (Edelmann, P., and C. Cremer, unpublished data).…”

“…The limited and different axial and lateral resolution of the confocal laser scanning microscope (~250 and 600 nm) also impairs the accuracy with which measurements of the 3D morphology of chromosome territories can be performed. Weighing the different sources of errors, which cannot be avoided with present technology, we assume that we likely underestimated the extent of shape and sur-face area differences that exist between the Xa and Xi territories (for further discussion see Bischoff et al, 1993;Eils et al, 1995a;Rinke et al, 1995).…”