Ultrastructure of the Mature Ungerminated Rice (Oryza Sativa) Caryopsis. The Germ

An in‐depth transmission electron microscope study of the ungerminated, unimbibed rice germ was conducted. All tissues in the germ were examined. Plastids were similar in all cells; many contained osmiophilic globules and phytoferritin, some displayed a limited thylakoid system, and all contained cytoplasmic tubular and vesicular inclusions formed by invaginations of the outer plastid membranes. Filament bundles were found in cells of the coleoptile, plumule, mesocotyl, radicle, and epiblast. Three general categories of cells could be identified in the germ based on protein body characteristics and on lipid body distribution: 1) Cells having inclusions in protein bodies and having numerous lipid bodies scattered throughout the cytoplasm; 2) Cells having or lacking protein body inclusions and possessing peripheral lipid bodies and/or having electron‐dense deposits in the lipid bodies; and 3) Cells lacking protein bodies and having peripheral lipid bodies.