MUCUS GLYCOPROTEIN GELS - A SCANNING ELECTRON-MICROSCOPY STUDY OF THE EFFECT OF CATIONS

Using rigorously controlled methods of sample preparation, mucus glycoprotein gels were observed to consist of a network of ducts and pores separated by membranous septa. This appearance has previously been shown to be a freezing artefact. The addition of a range of cations altered the appearance of the artefact by increasing the thickness of the septa and in some cases totally occluding the pores. A similar thickening was also produced by ethanol. Uncharged synthetic polymer gels (methylcellulose and polyvinylpyrrolidone) had an appearance identical to the glycoprotein gels and were similarly changed by the addition of cations. Methylcellulose gels also responded to the addition of alcohol or acetone. Only alcohol was effective in altering the appearance of polyvinylpyrrolidone. These results are interpreted in terms of macromolecular dehydration.