HIGH-PRESSURE FREEZING OF TISSUE OBTAINED BY FINE-NEEDLE BIOPSY

High-pressure freezing (HPF) permits adequate cryoimmobilization (with out detectable ice crystals after freeze-substitution) of biological t issue up to a thickness of about 200 mu m. Until now the preparation o f tissue prior to freezing has been unsatisfactory: sizing of the tiss ue to the required dimensions takes minutes, during which structural a lterations must occur. We demonstrate that the use of a fine-needle bi opsy technique minimizes tissue damage and guarantees sample dimension s close to the optimal thickness for HPF. The tissue cores can be cryo immobilized within 40 s of excision.