Richardson's Stain for Plastic Sections
For epoxy and methacrylate semithin sections.
Stock solutions.
A. 1.0% methylene blue in 1% borax
Methylene blue 1.0 gm
Sodium borate 1.0 gm
Distilled water 100 ml
B. 1.0% Azure II
Azure II 1.0 gm
Distilled water 100 ml
Working stain.
Mix equal volumes of stock solutions A and B.
Filter the stain periodically, or apply to sections be means of a syringe filter, to avoid precipitates.
Staining.
Dry sections down on a glass slide. Cover with a puddle of stain and heat on a warm hot plate for 30 to 60 seconds. Rinse off excess stain gently with distilled water or 70% ethanol. Dry the slide on the hot plate then coverslip the cooled slide with DPX.
Notes: DPX will cause sections of Spurr's epoxy to wrinkle unless mounted on carefully cleaned slides.
Be careful not to overheat the wet sections or steam bubbles may form under them.
Methacrylate sections may need shorter stain times to prevent high background from stain bound to the plastic. A brief rinse with 70% ethanol will remove this background at the risk of loosening the section from the slide.
Richardson, K.C., Jarrett, L., and Finke, E.H., Stain Technology 35:313 (1960), Embedding in epoxy resins for ultrathin sectioning in electron microscopy.