Figure 1.

The anatomy of sexual reproduction in Arabidopsis. A pistil is shown, with pollen at various stages of pollination. In a typical compatible pollination, pollen adheres to and germinates on the stigma, producing a pollen tube. The tube grows through the female tissues toward the ovary, where it needs to adjust its growth trajectory to find an ovule and then turn again to enter the micropyle and penetrate the embryo sac. White boxes indicate the main organs that take part in these interactions; blue boxes indicate the main processes (from adhesion at top left to fertilization at the bottom); red text indicates representative Arabidopsis mutants that affect these processes in any way; red arrows show the main cell-cell interaction between the male gametophyte (pollen grain and tube) and the different female organs and gametophyte (embryo sac). In Arabidopsis the whole process, from pollen adhesion to fertilization, takes about 4 to 8 hours.