Fig. 5. Irregular ovule development in AtMSI1-CS plants. Floral buds of stage 11-12 were either embedded, sectioned and stained with Toluidine Blue or cleared and observed with differential interference contrast (DIC) optics. (A) Section of a floral bud from a AtMSI1-CS plant. (B,C) Longitudinal and transverse sections of mature ovules of a wild-type plant. (D-G) Sections of ovules from AtMSI1-CS plants. (H) DIC image of a wild-type ovule. (I) DIC images of ovules from an AtMSI1-CS plant. (K,L) DIC images of ovules from stage 16 flower from AtMSI1-CS plants. Scale bars: 50 µm (C-G,I,K,L) and 100 µm (B,H). es, embryo sac; f, funiculus; i.i, inner integument; ms, megaspore; n, nucellus; o.i, outer integument.