A low temperature vacuum embedding procedure for X-ray microanalysis of biological specimens at subcellular level

The validity of freeze-drying and low temperature embedding in Lowicryl resins has been investigated in studies of ion distribution in mouse embryological inner ear, rat rib growth plate, liver and submandibular gland. The morphological preservation of the tissues was adequate for the identification of different intracellular compartments and extracellular structures. It was also possible to analyze extracellular fluids in the vestibular part of the developing inner ear. Compared with thin cryosections, Lowicryl sections are easier to produce and are more stable during analysis. Freeze-dried embedded material can be easily reorientated during cutting and adjacent sections can be used for other purposes such as histochemical and morphological investigations. We found that hydrophilic Lowicryl K11M, which is normally used for immunocytochemical investigations, also can be used for microanalysis. That opens the possibility for combined immunocytochemical and microanalytical studies. However, infiltration and polymerization steps have to be carried out at slightly higher temperatures than when the hydrophobic Lowicryl HM23 is used.