[Extent and spatial distribution of nucleolar RNA-synthesis in tissue fragments of riella after blockage of DNA-synthesis].

The synthesis of DNA in cells of tissue fragments from the wing of Riella is blocked specifically by treatment with 5-fluorodeoxyuridine. As a consequence of this blockage the nucleoli increase in size to about the 3-fold value of the control and show a higher intensity of staining specific for nucleic acids. Whereas in the control the increase in nucleolar size is restricted to a polar zone of the fragment, it spreads out over the fragment under the influence of FUDR.