Plastination: a new approach to morphological research and instruction with excised larynges.

Impregnation of biologic materials with curable polymer (plastination) allows wider use of human tissue for both basic and clinical research and instruction. The aim of this study was to determine for the first time the potential of this method in the field of laryngology. A feasibility study on 54 pig larynges established a detailed methodology for larynx plastination and determined the extent of shrinkage by using computer-assisted morphometry. The process involves dehydration, saturation with an appropriate intermediate solvent, and infiltration with cured polymer in vacuo. In the main study 20 fresh, intact human larynges and 12 laryngectomy specimens were submitted to plastination. The resulting resin blocks were cut with a diamond band saw into 0.8-mm sections in the transaxial plane. The resulting specimens are dry, odorless, and durable, and do not deteriorate with time. The subtle features of soft tissue pathology are well preserved. Shrinkage of plastinated larynges is less than 10%. The complete process is accomplished within 5 weeks. Staining of sections with toluidine blue provides an enhanced contrast between different types of tissue, allowing a clear identification of tumor invasion. Plastination is considerably faster than celloidin embedding and causes minor anatomic changes. It provides durable specimens of high quality for teaching purposes. In research, it allows the investigation of all tissue components in their undisturbed context in the borderline area between gross anatomy and histology.