Electron-cytochemical demonstration of acid phosphatase in saprophytic Claviceps purpurea

p-Nitrophenylphosphate in combination with lead salt technique was used for the cytochemical localization of acid phosphatase (EC 3.1.3.2) in saprophytic submerged culture of Claviceps purpurea Tul. The lead reaction product was found in capsular fibrils, in the newly formed parts of the cell wall and in the vacuoles of aged cells (autolysosomes). Phosphatase activity was present also in particulate intra-cytoplasmatic organelles. The concentric layering of lead deposits in these organelles indicates their relationship to endoplasmic reticulum membranes.