Prevention of penetration hindrance in cerium-based glucose-6-phosphatase cytochemistry by freezing tissue in melting nitrogen.

The demonstration of the ultrastructural localization of glucose-6-phosphatase in rat liver is hampered by penetration problems of the medium as appears from ultrathin cross-sections of vibratome sections. Besides the plasma membrane, also the cytoplasm forms a serious barrier for the penetration of the medium constituents. Prolonged preincubation for as long as 48 h at 4 degrees C in the complete incubation medium could not prevent the penetration hindrance. However, when employing 30 micron vibratome sections from tissue blocks that were frozen in melting nitrogen, the penetration hindrance was prevented.