Freeze-dried human leukocytes stabilized with uranyl acetate during low temperature embedding or with OsO4 vapor after embedding

Two new simple stabilization procedures for freeze-dried biological materia l are introduced which are compatible with low temperature embedding (LTE) in Lowicryl. The first method uses a Lowicryl K11M/HM20 mixture supplemente d with 0.3% uranyl acetate for LTE. For the second method polymerized Lowic ryl blocks containing the freeze-dried material are exposed to OsO4 vapor w hich penetrates into the Lowicryl block and stabilizes the embedded specime n. The quality of structural preservation is demonstrated with human leukoc ytes.