The cytokinesis-block micronucleus assay is a comprehensive method for measuring DNA damage, cytostasis and cytotoxicity. The assay consists in adding cytochalasin-B (an inhibitor of the mitotic spindle that prevents cytokinesis) to cell cultures. As a consequence, cells that have completed one nuclear division are identified by their bi-nucleated appearance. DNA damage events are scored specifically in once-divided bi-nucleated cells.

A scanning system operated by the Metafer software automatically scans in vitro MN samples, reliably identifies bi-nucleated cells (cells that underwent one cell separation after treatment), and analyzes them for the presence of micronuclei. Simultaneously, all mono-nucleated nuclei are counted, providing feedback on the proliferation rate of the culture.

Analysis results are displayed in a cell gallery, showing each single analyzed cell together with the respective micronucleus count. All data are summarized as histogram. Users can select the classes of micronucleus positive cells, filter the gallery by selection and, thus, quickly confirm automated results without the necessity to scroll through all cells. Cells and micronuclei morphologies are analyzed based on user-adaptable parameter sets. Parameter optimization and, thus, setting the scoring standards is done with the help of an automated self-optimization tool. Auto-optimization can also be used for finding the best image processing parameters.

Micronucleus scoring with the Metafer MNScoreX software is not just highly robust, but also extremely fast. It has become a very important tool for radiation biodosimetry. Several independent studies in peer-reviewed journals demonstrate that micronucleus scoring with Metafer MNScoreX is a useful tool for radiation dose estimation, especially in scenarios where a large accident involving sources of ionizing radiation is presumed.