Dr. Inaga took special note of these advantages. The starting point for her group’s application to renal biopsy was the staining material. She notes her insight that “platinum-blue stain would become a keyword”. It was a time of tightening limits on the use of uranyl acetate, the essential electronic stain. Platinum blue was gaining interest as a possible alternative, but none was available on the market for ready acquisition and use. Platinum blue was developed by Dr. Tanaka and his colleagues as a signal enhancer for LVSEM. Dr. Inaga proposed and patented the user-friendly stain kit that facilitated its utilization and led to its widespread adoption for TEM staining following reports at conferences and other venues of the highly effective differential staining of histopathologies by platinum blue in paraffin slices of rat- and mouse-tongue tissues, which are complex in composition.
When Dr. Inaga was further exploring the possibility of other applications, TEM personnel at Hitachi High-Tech Corporation suggested that renal biopsy sample would represent a particularly appealing application. The theory was that even though the observation would be by SEM, the kidney would be an appropriate target in view of the established method of diagnosis by TEM. Dr. Inaga notes that “As the doctor of pathology at Tottori University provided me with specimens that were from very representative cases, which enabled me to reveal the possibility of distinguishing of components in renal pathologic tissue using platinum blue.”