<prompt> Silver impregnation technique is used in the identification of -SpirochetesLeptospiraBorreliaAll of the above  <response>: Impregnation stains: - Cells and structures that are too thin to be visualized by the light microscope can be rendered visible by impregnation of silver on their surface. Silver impregnation method is a common method used for staining spirochetes, such as T. pallidum, Leptospira, Borrelia, etc. Histology Treponema pallidum grow in Rabbits testis. Brown color stained with Fontana Silver Impregnation stain. 