It sounds to me like these senescent cells have reached or completed telophase (construction of nuclear membranes after mitosis), yet cytokinesis (splitting of

It sounds to me like these senescent cells have reached or completed telophase (construction of nuclear membranes after mitosis), yet cytokinesis (splitting of the cell) has been inhibited. Perhaps during mitosis some kind of genetic integrity check is performed and failure halts cytokinesis (or success enables it).