A POSTEMBEDDING METHOD USING UREA-UNMASKED ULTRATHIN SECTIONS FOR THEELECTRON-MICROSCOPIC DETECTION OF SULFATED GLYCOCONJUGATES

Using urea-unmasked ultrathin sections, a postembedding staining metho d in combination with nitrous acid procedure has been established for the efficient visualization of sulfated glycoconjugates in a series of ultrastructures of three salivary glands of the rat. Pieces of the pa rotid, submandibular and sublingual glands from adult rats were subjec ted to glutaraldehyde-paraformaldehyde fixation, rinsed, dehydrated an d embedded in LR-White resin. Ultrathin sections were prepared, grid-m ounted, incubated in urea (6M) aqueous solution, and then stained with an alcian blue (AB) pH 1.0-phosphotungstic acid (PTA) sequence with o r without prior treatment with nitrous acid. The results obtained have shown that sulfated glycoconjugates are involved in such ultrastructu res as mast cell granules, basal lamina of arteriolar endothelial cell s and intercellular matrix of arteriolar smooth muscle cells.