Figure 6.

Histological analyses of the development of zygotic embryos using FCA staining. Cell walls are stained in blue, lignified or cutinised cell walls in orange to brownish red and nuclei in light purple. Zygotic embryo development starts within the ovules after pollination. Early stages (a: 0 d after pollination, b: 10 d after pollination) show ovules within the surrounding ovary tissue. The embryo sac and the micropyle are clearly visible. 30 d after pollination the endosperm becomes cellular and tiny multicellular embryos can be detected (c i to iii). 50 d after pollination globular shaped embryos have been formed (d i to iii). 60 d after pollination embryos become torpedo-shaped (transversal: e i to iii and longitudinal: f i to ii). 75 to 100 d after pollination zygotic (g and h, showing excised embryos) embryos reach their full size and maturation starts.