Abstract

A method of freezing cytological material for long term storage, based on a modification of that used in tissue typing for the storage of lymphocytes, was developed. The method entails the centrifugation of the specimen, adding 1 ml AB or fetal calf serum and 1 ml 20% dimethyl sulphoxide aliquoted into 2 ml tubes, and storage at -70 degrees C. Cytological detail was well preserved in a variety of samples including fine needle aspirates, urine, and bronchial brushings. Three dimensional architecture was also preserved. The method is practical, easy to perform, and allows retrospective studies to be undertaken with the subsequent use of a variety of special staining techniques, including immunocytochemistry.