Fig. 8. Morphological changes of pre-meiotic germ cell nuclei induced by hydroxyurea. Images are DAPI-stained nuclei in untreated (–HU) gonads and in those exposed to hydroxyurea (+HU). Upon HU treatment, pre-meiotic nuclei in the wild-type N2 gonad were substantially enlarged and reduced in number, but those in the wrn-1(RNAi) gonad were much smaller. Scale bar: 50 µm.