Uranyl Acetate (UA) en bloc Protocol
This is used to bring out unit membranes.
The stain is used just after osmium post-fixation and before dehydration.
It usually dissolves glycogen or renders it unstainable.
- pH 5.15 Maleate buffer: 11.6 g maleate/500 ml dH2O, adjusted to pH 5.15 with NaOH
- pH 6.00 Maleate buffer: 11.6 g maleate/500 ml dH2O, adjusted to pH 6.00 with NaOH
- 1% uranyl acetate in pH 6.00 maleate (pH drops on addition of uranyl acetate; dissolve by sonication)
- After osmication, wash tissue blocs in pH 5.15 maleate buffer (3 x 5 min).
If phosphate buffer was used previously, more extensive rinsing will be
necessary to prevent precipitation of uranyl phosphate. For thin retinal
tissue, 3 x 15 min should suffice.
- Stain in 1% uranyl acetate in pH 6.00 maleate for 1 hr at room temperature wrapped in foil (i.e. dark).
- Wash in pH 5.15 maleate buffer (3 x 5 min).
- Proceed to dehydration.
Farquahar and Palade, J CEll Bio 26:263, 1965.
Trelstad, Revel and Hay, J Cell Bio c-6, 1966.