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.
No takes yet. Share an insight, caveat, or question.
Mueller et al. (1978) studied this question.