MORPHOLOGIC AND CYTOCHEMICAL IDENTIFICATION OF PEROXISOMES IN THE RAT PAROTID AND OTHER EXOCRINE GLANDS
Peroxisomes were identified in all three parenchymal cell types of the rat parotid gland. They averaged 0.33 µ in diameter in the acinar and intercalated duct cells, and 0.22 µ in the striated duct cells. They were closely related to the endoplasmic reticulum, occasionally in continuity with smooth surfaced cisternae and often embraced by ribosome-free portions of endoplasmic reticulum which paralleled their membrane. Glutaraldehyde fixation inhibited the endogenous peroxidase of the parotid gland and allowed visualization of the peroxisomes following incubation in alkaline diaminobenzidine medium. Peroxisomal staining was unaffected by varying H2O2 concentrations or low concentrations of KCN, but was prevented by aminotriazole and dichlorophenolindophenol. Examination of other exocrine glands after incubation in diaminobenzidine medium revealed the presence of peroxisomes in the pancreas, submandibular, lacrimal, nasal mucosal and von Ebner's glands. These studies indicate that peroxisomes are of widespread occurrence in exocrine tissues of the rat.