The PAP PEN is most useful for immunity staining ( PAP method, ABC method, etc.) and fluorescent antibodies method in carrying out the maximum efficiency with minimum amount of extremely valuable antiserum.
Sections should be quickly deparaffinized by xylene, then washed out with ethanol; dry or wipe away excess liquid around the section on the glass slide with tissue paper. Encircle the section on a glass slide with the PAP PEN as shown below in the illustration, and dry the circle for 1-2 minutes at room temperature; then soak the section in a phosphoric acid buffer solution (PBS or TBS), for about 5 minutes.
The PAP PEN makes a water repellent circle which avoids the need to wipe around the section after every staining. Circle made by the PAP PEN is removable by xylene. Since it is not influenced by water-soluble mounting media, there is no interruption in microscopic observation. This water repellent PAP PEN is applicable not only to immunity staining but also to ASD staining and/or Enzyme staining.
Glass slides must be cleaned by xylene and ethanol or coated with egg-albumin glycerine or poly-L-lysine before the PAP PEN is applied.
Note: If the surface of the glass slide is treated with hydrophile, it is necessary for the glass slide to soak in a 0.1N hydrochloric acid solution for about 30 seconds and then dry it after washing it with water in order to prevent the circle from disappearing.