An Improved Method for the Retention of Globoids in Aleurone Grains in Light and Electron Microscopy

[摘要] This paper deals with preparations for the preservation of globoids in the seeds as well as with some histochemical and ultrastructural characteristics. In the preliminary examination on the extraction of metachromatic substances from globoids in aleurone grains of plant seeds and of authentic phytin specimens, the substances were extracted within 15 minutes at pH values lower than 4 and higher than 11 and within 12 hours at pH 7 while not extracted in the pH range 8 to 10. Further experiments were performed to determine an available procedure for the retention of globoid. Some aldehydes and osmium tetroxide produced usable images but permanganate did not produce any acceptable image. Cacodylate buffer was preferable to phosphate buffer. In the usual procedures of fixation and dehydration, the overall time within 6 hours was recommended because a prolonged time caused the decrease in size of globoid owing to the extraction of substances from the globoid. The images such as large globoid cavities and absence or very small size of globoids in aleurone grains seem to be an artefact occurred during the preparation of materials. The addition of cations such as magnesium and calcium to the fixatives and the dehydration series was suggested to reduce the loss of materials in the globoids. In the uranyl staining of thin section, the uranyl acetate in a sodium acetate or a veronal acetate buffer at pH 6 was used to prevent the extraction and dispersion of electron dense substances from globoid. As embedding media, glycol methacrylate and Spurr's epoxy resin were the most available for light and electron microscopies, respectively. The nature of globoid as a phytin containing particle was confirmed with histo-chemical and ultrastructural methods. Inclusions in aleurone grains and lipid granules among several seeds were compared. On the base of these results, the terminology of inclusions in aleurone grains of lettuce seed and the localization of phytin in globoid of sorghum seed were discussed.

[学科分类] 农业科学（综合）