Ultrastructural demonstration of cartilage acid glycosaminoglycans

Ruthenium Red staining of ultrathin sections of human mast‐cell granules*

“…Since Luft (1964) introduced Ruthenium Red for the electron microscopy of acid mucopolysaccharides, several authors have used the dye for electron microscopic studies. The dye solutions were prepared either in phosphate buffer at pH 7.2 (Gustafson & Pihl, 1967;Pihl et al, 1968) or in 0.1 M cacodylate buffer at pH 7.4 (Luft, 1964) at concentrations of 0.001 M (Pihl et al, 1968), 0.05y0 (Gustavson et al, 1967) and 1500 p.p.m. (Myers et al, 1969), together with about 6O glutaraldehyde as fixative.…”

“…(Myers et al, 1969), together with about 6O glutaraldehyde as fixative. Meyers, Highton & Rayns (1 969) used Epon for embedding and obtained sufficient contrast without section staining, while Pihl (1967) andPihl et al (1968) stained Epon-embedded ultrathin sections with lead citrate or uranyl acetate to obtain further contrast. Also, in an attempt to obtain better contrast, these authors changed from Epon to glycomethacrylate.…”

“…However, problems of adsorption and penetration of the dye into the tissue blocks remain unsolved. Furthermore, if Epon 812 is used for embedding, the contrast of the tissue components which are stained beforehand by Ruthenium Red in the fixative seems to be reduced during the embedding procedure (Gustafson & Pihl, 1967;Pihl et al, 1968). The present study attempts direct application of Ruthenium Red onto the Epon-embedded ultrathin sections.…”

“…Ruthenium Red has formerly been used for electron microscopy of tissue components rich in acid mucopolysaccharides such as mast-cell granules (Gustafson & Pihl, 1967), the mucinous coat of intestinal epithelial cells (Luft, 1964), ground substance of cartilage (Pihl et al, 1968) and synovial connective tissue (Myers et al, 1969). In these earlier studies, the dye was added to the glutaraldehyde fixative, following which the specimens were osmicated.…”

Biochemical peculiarities of the guinea pig and some possible examples of convergent evolution

“…These observations are presumably related to the replacement of the zinc-binding histidine residue at B10 by asparagine or glutamine in the guinea pig and coypu, respectively, and the change of several hydrophobic residues at contact points strategic for hexamer formation to hydrophilic residues, making the guinea pig insulin molecule more stable in the monomeric form . It is also of interest that guinea pig beta cells are thought to contain amorphous, not crystalline, material, and little or no zinc (Pihl and Falkmer 1967;Pihl 1968;Falkmer 1971;Lange 1973).…”