Fixation of plant tissue

Abstract

Electron micrographs of mature plant cells fixed in neutral osmium tetroxide solutions frequently show disrupted cell membranes and an apparently dispersed cytoplasm. In the case of young non-vacuolated plant cells their fixation has been improved by the addition of various agents such as Locke’s medium and dextrin (1) or sucrose (2) to a buffered osmium tetroxide fixation medium. Presumably these additives tend to prevent the swelling of cell components. Another source of damage in turgid vacuolated cells may be the destruction of the differential permeability of the tonoplast during the early stages of fixation. This occurrence would be accompanied by a loss of turgor resulting in a disturbance of the partly fixed cytoplasm of the initially distended cell. Such damage may be expected to be apparent particularly at the cytoplasm-cell wall boundary. Further disruption of the cytoplasm could result from the sudden release of vacuolar fluid into the cytoplasm.