Cytochemical localization of exogenous peroxidase in adrenal medullary cells of hamster.

The endocytosis in hamster adrenal medullary cells has been studied by intravenously administered horseradish peroxidase, which was then detected with the Graham-Karnovsky method. The protein uptake was investigated 30, 60, and 120 min after the peroxidase injection. The exogenous protein was accumulated mostly in the lumen of the sinusoids, around the capillaries as well as at the apical pode of chromaffin reaction product was detectable also in the chromaffin cells. The protein uptake was very intensive beside the plasma membrane, both apically and laterally, through coated- and smooth-surfaced vesicles. Two hours after peroxidase injection, the majority of the reaction product was present in multivesicular bodies. It is supposed that the primary endocytotic vesicles were taken up by multivesicular bodies and digested by lysosomal enzymes. The ultimate fate of the incorporated granule's membranes seem to be digestion by lysosomal enzymes, thus they are not reutilized during granulogenesis in the chromaffin cells.