Scanning Electron Microscopy


The chemical literature suggests that pyridine derivatives are the major reaction products of amine-aldehyde reactions. A scheme is proposed for pyridine synthesis which is derived from a classic synthesis of pyridines from one amine molecule and 3 aldehyde molecules. The pyridine polymers are considered as a major class of cross-links in glutaraldehyde fixed cells. This scheme for pyridine synthesis accounts for the following observations of amine-glutaraldehyde react ions: 1) large quantities of acid are rapidly produced, 2) oxygen uptake occurs at a high rate, 3) a variety of products distinguished by molecular size are rapidly and irreversibly synthesized, and 4) the major reaction products share physical and chemical characteristics with highly substituted pyridine compounds. When formaldehyde is added to glutaraldehyde-amine reactions, oxygen uptake is sharply reduced and the product spectrum is changed in a complex manner. Formaldehyde may thus have an entirely different role in the mixed glutaraldehyde-form-aldehyde fixatives than has previously been suggested.

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