Abstract
Lead salts show affinity for a wide range of cellular structures and they increase general contrast much more intensely than any other known electron stain. However, lead stains do not show a strong affinity for nucleic acids, especially DNA. Since uranyl salts exhibit special affinity for nucleic acids, double staining of sections with uranyl acetate followed by lead acetate has become quite popular. Uranyl acetate is also an excellent fixative provided the tissue is treated with this reagent prior to dehydration. After double fixation with glutaraldehyde and osmium tetroxide, uranyl acetate treatment prior to dehydration markedly improves the preservation of all cell components especially that of nucleic acids, ground proteins, myofibril including Z bands, and mitochondrial matrix. Thus, when employed prior to dehydration, uranyl acetate acts not only as a stain but also as a general fixative for both nucleic acids and proteins (Hayat, 1969). Uranyl acetate is so easy to apply to both the tissue block and the sections that there seems no reason for not routinely using it for general staining. In the present study, tissues were exposed to uranyl acetate twice. The details of the method used are given below.
Published Version
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