Fig. 6. Loss of Drosophila citron gene function results in a dramatic reduction in imaginal disc size. Imaginal discs from wild-type (A,C,E,G) and cit²/Df(3)iro-2 mutant (B,D,F,H) third instar larvae labelled with Hoechst 33258 to detect DNA (A,B) or with anti-PH3 to detect cells in mitosis (C,D, shown at high magnification) or labelled using TUNEL to detect cells undergoing apoptosis (E,F and high magnification in G,H). Transheterozygous mutant imaginal discs exhibit a dramatic reduction in size (e.g. leg discs shown in B, compare with wild type in A), contain fewer cells progressing through mitosis (compare D with C) and many more cells undergoing apoptosis (compare mutant wing disc in F and H with wild type in E and G). Scale bars: 25 µm.