Localization of chromatin in "persistent" nucleoli in okadaic acid treated HeLa cells

In okadaic acid treated HeLa cells, the chromosomes sometimes condense without being accompanied by nuclear envelope breakdown. These cells show "persistent" nucleoli. Within these "persistent" nucleoli the intranucleolar chromatin condenses and can be observed in the region of the dense nucleolar component (DNC) of the nucleoli. Other nucleolar components, namely the fibrillar centre (FC) and the granular component (GC) remain unchanged. These observations strongly speak for the localization of nucleolar chromatin (ribosomal cistrons) within the dense nucleolar component of the interphase nucleolus.