Figure 1

Developmental stages of H. perforatum ovules sampled and analyzed in this research. A: Schematic representation of key aspects of sexual and apomictic reproductive pathways in H. perforatum and key developmental stages. B-G: Ovules at developmental stages spanning meiosis, aposporic initial formation and development, and gametogenesis. B: megaspore mother cell (MMC); C: tetrad showing a functional megaspore (fM) along with three degenerating megaspores (dM); D: aposporic initial (Ai) cell; E: enlarged aposporic cell equivalent to an aposporic one-nucleate embryo sac (a1N ES); F: oangic apparatus showing in focus one synergid (Syn) and the egg cell (EC); G: detail of a central cell (CC) from a mature embryo sac. In each photograph the yellow area mark a given germinal cell type (each bar is 8 μm).