Fig. 3. Developmental series of ovule development in wild-type, er-105 erl1-2/+ erl2-1 and er-105 erl1-2 erl2-1/+ Arabidopsis. (A-L) DIC images of ovules at stages: 1-II (A,E,I); 2-III (B,F,J); 3-I II (C,G,K) and 4-I (D,H,L). Differences in development are seen at stage 3-I-II (C,G,K). Asymmetric growth of the outer integument occurs in all genotypes; however, er-105 erl1-2 erl2-1/+ integuments appear less organized and gametophyte development has ceased (K). By anthesis (D,H,L), the integuments of er-105 erl1-2 erl2-1/+ are short resulting in the nucellus protruding from the integuments (L). By contrast, the er-105 erl1-2/+ erl2-1 ovule has nearly normal appearance, with a very subtle phenotype (H). (M,N) er-105 erl1-2 erl2-1/+ ovule at stage 2-V with tetrad (M, bracket) and stage 3-II (N) showing two-nuclear gametophyte. MMC, megaspore mother cell; n, nucleus; ii, inner integument; oi, outer integument. Scale bars: 20 µm.