Methacrylate Embedding and Sectioning of Calcified Bone

Abstract

Twenty-five milliliter aliquots of ethyl-butyl (11) methacrylate were polymerized at 6 or 7 initiator concentrations using 3 polymerization temperatures, both in air and in a water bath. Duplicate series were polymerized with and without vibration, pre-polymerization, and exclusion of oxygen. Hardening times and maximum temperatures reached within the samples were recorded. Vibration and the exclusion of oxygen had no effect. Prepolymerization, increasing polymerization temperature and increasing initiator concentration all decreased the hardening time and increased the maximum temperature. Polymerizing in a water bath rather than in air reduced the maximum temperature by 25-40[degree]C and lengthened the hardening time about 1 hr. An initiator concentration of 0.4% Luperco CDB in ethyl-butyl methacrylate and a water-bath temperature of 45[degree]C were selected for tissue embedding. The hardening time was 8 hr and the maximum temperature during polymerization was about 60[degree]C. Split rat femora and tibiae were freeze-dried and vacuum-infiltrated with acetone, absolute alcohol or monomer. The acetone or alcohol-fixed specimens were subsequently infiltrated with monomer. The specimens were transferred to 1 oz bottles, prepolymerized syrup added, and polymerized. No consistent differences between specimens treated by these methods were noted. Five-micron serial sections could be cut using a Leitz sledge microtome with a modified knife if the block was coated with paraffin between sections.