Fig. 3. Histological analysis of microsporogenesis. Transverse sections of anthers are displayed in developmental sequence, showing the progress in microsporogenesis in various genotypes. ga1-3 anthers developed normally up to the tetrad formation stage (stage 7) but after this, they diverted from the normal (compared with stages 9-12 in wild type; ga1-3 stages highlighted with question marks). Eventually, all ga1-3 pollen sacs aborted (last two photos). ga1-3 plants lacking RGL1, RGL2 and RGA (Q2), or RGL1, RGL2, GAI and RGA (penta) successfully completed microsporogenesis and released mature viable pollen grains. Scale bar: 50 µm. Microsporogenesis stages are indicated in bottom right-hand corner of the pictures.