mouse LD50=100 mg/kg

Pea embryos were dissected from developing seeds of pea plants (Pisum sativum) grown in pots in a greenhouse and irrigated with water. Embryos from pea and leaf fragments from A. thaliana and tomato (Lycopersicon esculentum) were vacuum-infiltrated with the fixation solution containing 2% (w/v) paraformaldehyde, 1% (v/v) glutaraldehyde, 1% (w/v) caffeine in 100 mM phosphate buffer (pH 7) for 30 min and incubated for 15 h in the same solution. The fixed samples were washed with 0.1 M phosphate buffer (pH 7.4) three times and dehydrated in successive baths of 50, 70, 90, 95, and 100 ethanol, butanol/ ethanol 1:1 (v/v), and 100% butanol. Then, the tissues were embedded in the Technovit 7100 resin (Heraeus Kulzer) according to the manufacturer’s instructions, and thin sections (5 mm) were made. The sections were deposited on glass slides that were incubated for 45 min in Perls stain solution, except for negative controls. After washing with distillated water, the glass slides were incubated in a methanol solution containing 0.01 M NaN3 and 0.3% (v/v) H2O2 for 1 h and then washed with 0.1 M phosphate buffer (pH 7.4). For the intensification reaction, samples were then incubated between 10 and 30 min in a 0.1 M phosphate buffer (pH 7.4) solution containing 0.025% (w/v) DAB (Sigma), 0.005% (v/v) H2O2, and 0.005% (w/v) CoCl2 (intensification solution). Rinsing with distilled water stopped the reaction