<prompt> Silver impregnation technique is used in the identification of ?SpirochaetesLeptospiraBorreliaAll of the above  <response>: Silver impregnation: cells and structure too thin to be seen under the ordinary microscope may be rendered visible if they are thickened by impregnation of silver on the surface. Such a method is used for the demonstration of spirochetes and bacterial flagella REF:Ananthanarayan Panickers Textbook of Microbiology 9th edition pg no:13 