CHROMATIN CONDENSATION IN ERYTHROPOIESIS RESOLVED BY MULTIPIXEL SPECTRAL IMAGING - DIFFERENTIATION VERSUS APOPTOSIS

Chromatin condensation and nuclear organization of May-Grunwald-Giemsa (MGG)-stained normal erythropoietic bone marrow cells and apoptotic r ed cell precursors were resolved by spectral bio-imaging. Multipixel s pectra were obtained from single cells displaying a range of wavelengt hs of both transmitted and absorbed light. Two groups of spectra, of l ow-and high-intensity transmitted light, were revealed in the nuclei o f each cell. The absorbance spectra served for the reconstruction of ' 'absorbance images'' depicting the affinity of MGG stain for the chrom atin of proerythroblasts and of basophilic, polychromatic, and orthoch romatic normoblasts. The localization of different spectral components in the nuclei was resolved employing two mathematical methods, spectr al similarity mapping and principal component analysis. Novel structur es of high symmetry revealing windmill-like organization were detected in basophilic, polychromatic, and orthochromatic normoblast cells. Ma tching structures were detected in apoptotic normoblasts obtained from an agnogenic myeloid metaplasia patient. Apoptosis was associated wit h a gradual breakdown of the ordered arrays in the nucleus. We propose that DNA cleavage may lead to fragmentation of the symmetrical windmi ll-like superstructure of the basic nuclear domains.