PMID: 591575Jan 1, 1977

A light- and electron-microscope study of nuclear structure throughout the cell cycle in the euglenoid Astasia longa (Jahn)

Journal of Cell Science
N ChalyJ G Lafontaine


The structure of nuclei of Astasia longa in synchronized cultures was examined at the light- and electron-microscope levels. Three types of nuclei, differing mainly in chromatin conformation, were observed during interphase and were tentatively classed in the G1, S and G2-periods. The fibrillar nucleolar regions exhibited a most complex organization and appeared to consist of convoluted, coarse filaments or nucleolonemata approximately 0.15 micrometer in diameter. Chromosome condensation was evidenced first by the longer, thicker profiles of chromatin observed in late prophase. Furthermore, the nucleolus, that persists throughout mitosis, began to elongate at late prophase. Furthermore, the nucleolus, that persists thorughout mitosis, began to elongate at this stage, simultaneously with the appearance of short, unoriented profiles of intranuclear microtubules. Chromosome condensation was complete by mid-metaphase and the nucleolus was elongated into a cylindrical shape with irregular extremities. Microtubule profiles were longer than in prophase; they were now oriented parallel to the nucleolus and frequently lay closely appressed to its sides. In anaphase, the chromosomes segregated into 2 groups, one towards each extremity of...Continue Reading

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Cell Cycle
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