Structural variations of different oral basement membranes revealed by cationic dyes and detergent added to aldehyde fixative solution.

The ultrastructural appearance of different types of basement membrane was studied using histochemical methods for visualizing glycosaminoglycans. Samples of rat gingiva and mouse molar germ tissue were fixed either with glutaraldehyde, glutaraldehyde-ruthenium hexammine trichloride (RHT), glutaraldehyde-Cuprolinic Blue (CB) or cetylpyridinium chloride-glutaraldehyde (CPC). Ultrathin sections were stained with uranyl acetate and lead citrate. The results showed that the conventional trilaminar structure of the basement membrane was observed after glutaraldehyde and CB fixation. In contrast, after CPC or RHT fixation, the appearance of the basement membrane was homogeneous without any evidence of a lamina lucida. Furthermore, after single fixation with CPC, the ultrastructure of different basement membranes from oral tissues showed some differences in appearance which were related to their localizations, functions, or both.

Autometallographic visualization of glycosaminoglycans in the tongue mucosa of rats using cuprolinic blue and enzymatic digestions.

In order to visualize by light microscopy the glycosaminoglycans (GAGs) in the rat tongue mucosa, the tissue was fixed with cuprolinic-blue (CB)-aldehyde and the staining enhanced by autometallographic (AM) procedure. As other polyanions were also detected, enzymatic digestions with hyaluronidase, chondroitinase ABC and pronase were performed on these tissues in order to test the specificity of the staining. Chondroitinase ABC caused a dramatic decrease of silver grains in the lamina propria whereas hyaluronidase and pronase induced only discrete or no modification. This supported the concept that the GAGs visualized by CB and autometallography in this area as dermatan sulphate. The other polyanions (mostly DNA and RNA) seen in the epithelial layers were unaffected by these enzyme treatments.