Interim Report of the Committee on Histologic Mounting Media: Resinous Media

Abstract

The Fisher “Permount” naphthalene polymer, the Hartman Leddon “H.S.R.” terpene polymer resin, a Monsanto polystyrene P-1, the Will Corporation “Diaphane” and “Green Diaphane”, and the du Pont “Lucite” methyl methacrylate polymer were examined, and the possibility of use of some other plastics was also explored. The first 5 mentioned were tested for color preservation of a variety of stains in comparison with Canada balsam and Clarite X. From this point of view polystyrene, the Hartman Leddon “H.S.R.” and the Fisher “Permount” resins were the most satisfactory, then the “Diaphanes”. Both “Permount” and “H.S.R.” show some yellowing. The H.S.R. with a melting point of 115°C, the Permount with 150°C. melting point, and the Polystyrene with a thermal denaturation point above 220°C. all excell Canada balsam in heat resistance. Trimethylbenzene, cymene and monoamylbenzene appear to be the best solvents for polystyrene. Mounts made in a solution of 20 g. polystyrene in 100 ml. trimethylbenzene can be packed flat slide to slide in 24 hours after mounting without sticking together. This report is not intended to deprecate the use of other resinous mounting media which have not as yet been tested or compared with those mentioned herein.