Fig. 5
From: Unraveling the development behind unisexual flowers in Cylindropuntia wolfii (Cactaceae)
Fertilization of the egg (EG) by pollen tube (PT) in megagametophyte (MG) of ovules of female flowers. The pollen tube enters through the micropyle (MI). The megagametophyte is surrounded by nucelle (NU), internal integument (II) and external integument (EI), which in turn is surrounded by the funicle (FU). Four cells are found at maturity including the central cell (CC), two synergids (S, only one visible) and the egg (EG)