An ultrastructural assessment of mitochondria in the gastric parietal cell with the high iron cliamine method

Summary The ultrastructural densification of mitochondria by the high iron diamine (HID) method has been investigated by staining gastric parietal cells with each component of the HID reagent, alone or in combination, or with an otherwise modified HID solution. The effect of certain chemical treatments prior to staining has also been assessed. These tests provided evidence for at east three cytochemically distinguishable constituents in the mitochondrial matrix. In addition, the results from these tests and observations obtained with a newly introduced diaminobenzidine (DAB)-FeCl₃ staining reagent indicated that the probable mode of action of the HID method in imparting density to mitochondrial matrix entails combination between a complex of iron with polymerized or aggregatedm- andp-diamine and some matrix constituent. Assessment of the cytochemical staining in varied fixation condition revealed that the lucent population of mitochondria recently described in HID-stained parietal cells reflects a failure to stain with the method because of inadequate fixation.The possible nature of the HID-reactive substance in the mitochondrial matrix is discussed in the light of these observations and other cytochemical reactivities.