The Ultrastructure of Phenolic-Storing Cells Fixed with Caffeine

Abstract

Caffeine at concentrations between 0.1% and 1% caused the condensation of phenolics inside the vacuoles of phenolic-storing cells prepared for electron microscopy. Caffeine added to the glutaraldehyde and washing buffer during fixation prevented the leaching of the phenolics into the cytoplasm. Phenolic-storing cells so treated had a cytoplasm similar in appearance to that of cells not storing phenolics. In contrast, mature phenolic-storing cells fixed without caffeine had a dense, osmiophilic cytoplasm. The appearance of the cytoplasm in these cells thus appears to represent an artefact of fixation.