The fine structure of the embryo of Lactuca sativa. I. Dry embryo

Abstract

Dry embryos of Lactuca sativa L. var. Grand Rapids were studied by improved techniques of light and electron microscopy. Cells of the dry embryo are filled with reserve proteins and lipids; the latter are preserved in the processed material only if the material is fixed in osmium tetroxide at some stage before dehydration and embedment. Nuclei, mitochondria, ribosomes, and some membranes show the least modifications in the dry state; other organelles are poorly defined and some may be absent. The best definition of organelles and membrane systems is found in the root apical cells, least in the cortical cells of the hypocotyl and mesophyll cells of the cotyledons.