Fig. 4. RNA in situ hybridisation of selected genes during wild-type floral development. (A,B) At4g21590. The arrows show expression in the centre of a stage 3 bud (A), and later in developing stamens (B). (C) At1g13400. Arrows indicate expression in emerging stamen primordia (st), and in the placental region in early carpels (ca). (D,E) At3g17010. Expression in emerging stamen primordia (st) is indicated in D; arrows in E indicate expression in the sporogenous tissue of stamens (st) and in the placental region of carpels (ca). (F) Expression of GA4 in stamen filaments (arrow). (G,H) Expression of ATH1 in developing stamens (st). For better contrast, the sections in A, B, G and H were photographed in aqueous medium, before the tissues were permanently mounted.