Abstract: The invention relates to a fixative composition for preservation of tissue and biological samples. Current fixative compositions have the drawback that they do not sufficiently protect against DNA/RNA degeneration. In addition their use impairs extractability and compromises amplifiability of extracted DNA. The invention solves the combined but related problems and provides a fixative composition comprising one or more alkanols, polyethylene glycol having a molecular weight of 200-600, one or more weak organic acids in a combined concentration of 0.01 to 0.10 mole per liter of the fixative composition, and water. The fixative composition is essentially free of any cross-linking agents such as formaldehyde.

Abstract: A semi-automated method of classifying a histological specimen for the presence of premalignant or malignant cells, including the steps of treating a specimen with an immunohistochemical marker to provide a visual indication of cell proliferation, ranking individual objects in the specimen in an order according to the likelihood that each object has attributes consistent with a premalignant or malignant cell or cell cluster, selecting for display a set of said objects according to said ranking, and displaying images of said selected objects to facilitate review by an operator.

Abstract: The preparation of paraffinized cell blocks from fixed tissue and sputum samples employs microwave enhanced dehydration and impregnation of the cell specimens. The fixed cell specimen is first exposed to a suitable dehydrating agent, typically a low molecular weight alcohol, and exposed to microwave radiation for a relatively short period of time. The dehydrated sample is then cleared (if necessary) and immersed in a suitable melted wax and thereafter exposed to microwave radiation again for a relatively short period of time. The resulting paraffinized tissue sections have been found to possess staining characteristics which are substantially equivalent or superior to those obtained by conventional cell block paraffinization techniques.