Histological preparation of implanted biomaterials for light microscopic evaluation of the implant-tissue interaction

A technique is presented for processing implanted biomaterials with surrounding soft tissue for histological assessment of the implant-tissue interaction. Specimens are removed with the implant-tissue interface intact, fixed in formalin, dehydrated in a graded series of ethanol followed by a graded series of acetone in ethanol, and embedded in Spurr's low viscosity epoxy resin. Sections 0.5-1.0 mm thick are cut from the cured blocks using a metallurigical saw with a diamond wafer blade. After being glued to glass microscope slides, they are ground and polished to approximately 75 microns in thickness. The polished sections are treated with 95% ethanol saturated with sodium hydroxide, stained with Gill's hematoxylin and counterstained in eosin Y-phloxine B. The sodium hydroxide solution degrades the resin, allowing the stain to penetrate the tissue. By limiting the time in sodium hydroxide, the depth of staining is controlled and one is able to simulate a thin paraffin section with high resolution of the implant-soft tissue interface.