Preservation of tissue mucins by freeze‐drying and vapour fixation

SYNOPSIS The fixation of tissue mucins with liquid fixatives is unsatisfactory because of their solubility. Diffusion may be avoided, however, if the mucins are fixed in situ without contact with any liquid fixative. The method of fixation here described consists of freeze‐drying followed immediately by treatment with fixatives in the gaseous state, at elevated temperatures. Rat submaxillary salivary gland was used as test material since it contains several types of mucin with distinct localizations. The results of fixation of freeze‐dried tissues with formaldehyde vapour, osmium tetroxide vapour, and glutaraldehyde vapour, are far superior to those of the methods generally employed. With acrolein vapour and chromyl chloride vapour preservation of mucins is unsatisfactory. The chemical effects of vapour fixation have been explored by studying the protein histochemistry of the tissues.