Figure 3.

MEA transcription in the central cell before and after fertilization. (A) Two haploid polar nuclei in the unfertilized central cell; a single nuclear dot is localized in each nucleus. (B) A tetraploid nucleus (resulting from the fusion of two diploid polar nuclei in a tetraploid ovule) showing four nuclear dots prior to fertilization. (C) A diploid polar nucleus in the central cell of a diploid ovule prior to fertilization showing two nuclear dots. (D) The triploid nuclei resulting from the division of the primary endosperm nucleus, each showing two nuclear dots after fertilization. (E) Two nuclear dots in the triploid endosperm nuclei located at the chalazal pole of the embryo sac. Bar, ∼0.5 μm in A; 1.2 μm in B; 1.4 μm in C; 1.5 μm in D; 1.7 μm in E.