The incubation of unfixed tissues for electron microscopic histochemistry

Summary Small tissue blocks of various organs of the rat were incubated for gradually increasing times in a neutral buffer-sucrose medium modelling the main parameters of the histochemical incubations. Following incubation the blocks were fixed in paraformaldehydeosmium and embedded in Durcupan. The electron microscopic study revealed that even after 40 minutes of incubation prior to fixation, fine structure is preserved satisfactorily from the histochemical point of view. With consideration to further advantages of such a proceeding, the incubation of unfixed tissue blocks for electron-histochemistry is recommended.