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Updated: Aug 9, 2026
A Cell Free Assay to Study Chromatin Decondensation at the End of Mitosis
Published on: December 19, 2015
Behavior of interchromatin granules during the cell cycle
1Laboratory of Cellular and Tissular Biology, University of Liège, Belgium.
Insights
Interchromatin granules (IGs) persist throughout the entire cell cycle, forming distinct clusters during interphase and dispersing during mitosis. These RNA-containing structures are vital components of the cell nucleus.
Area of Science:
- Cell Biology
- Molecular Biology
- Cytogenetics
Background:
- Interchromatin granules (IGs) are nuclear structures observed during the interphase of the cell cycle.
- Their precise role and behavior during mitosis have remained largely unclear.
Purpose of the Study:
- To investigate the ultrastructural behavior of interchromatin granules (IGs) during both interphase and mitosis.
- To determine if IGs persist throughout the entire cell cycle.
Main Methods:
- Utilized cytochemical and immunocytological approaches at the ultrastructural level.
- Examined HEp-2 and Ehrlich tumor cells.
- Employed serial section analysis, silver staining, EDTA staining, and immunogold labeling for polyadenylate nucleotidyl transferase.
Main Results:
- Identical IG behavior was observed in both cell types.
- IGs form distinct clusters in interphase nuclei, associated with coiled and fibrillar bodies.
- During mitosis, IG clusters disperse into the cytoplasm and reform within daughter nuclei after chromosome decondensation.
Conclusions:
- Interchromatin granules (IGs) are stable structures that persist throughout the entire cell cycle.
- IGs are consistently associated with RNA, as indicated by polyadenylate nucleotidyl transferase labeling.
- The dynamic behavior of IGs during mitosis suggests a role in nuclear reformation.
Abstract:
We investigated at the ultrastructural level, by different cytochemical and immunocytological approaches, the behavior of interchromatin granules (IGs) during interphase and mitosis in two cell lines (HEp-2 and Ehrlich tumor cells). Identical results were found in all two cell types. In interphase cells, IGs group into irregular clusters of varying size. They are frequently associated with coiled bodies and homogeneous fibrillar bodies. Analysis of serial sections reveals that IG clusters occupy distinct regions within the nucleoplasm. During prophase, the aggregation of granules in these clusters gives rise to compact, spherical, granular structures. These disperse in the mitotic cytoplasm at the breakdown of the nuclear envelope. At early telophase, some of them come into close contact with the periphery of reforming nuclei. IG clusters reappear in the daughter nuclei only after the chromosomes have decondensed during late telophase. Concomitantly, the cytoplasmic granular structures disappear. During the cell cycle, IG are silver-stainable and EDTA-positive. They are also constantly labeled by the polyadenylate nucleotidyl transferase-immunogold technique for detecting RNA. These results support the view that IGs persist throughout the whole cell cycle.
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