Fig. 7. Light micrographs of mid-torpedo embryos. At the mid-torpedo stage, wild-type (A,C) and sibling ise1 mutant (B,D) embryos are similar in cell size and regular patterns of cell division (arrows) both in the hypocotyl (A,B) and the radicle (C,D) viewed with Nomarski optics. Toluidine Blue staining of hypocotyl thin sections of wild-type (E) and mutant (F) embryos shows that cells in the provascular regions (pv) are narrow and elongated in both. Vacuoles (v) in mutant cells (F) are larger in size and fewer in number than in cells of wild-type (E). Scale bars, 40 µm.