An ultrastructural study of goblet cells in rat nasal mucosa as revealed by the quick-freezing method

In order to clarify the natural ultrastructure of goblet cells in the rat nasal mucosa, they were examined by the quick-freezing and freeze-substitution (QF-FS) or deep-etching (QF-DE) methods for comparison with conventional fixation methods. Some nasal mucosal tissues were unstimulated; others were stimulated with acetylcholine or substance P. The QF-FS method yielded fewer artefacts on transmission electron microscopy than conventional fixation methods. In the stimulated goblet cells, most of the secretory granules appeared to be loose in the matrix and more distorted in shape. By the QF-DE method, they were observed 3-dimensionally to be larger in size and aggregated together. In contrast, the secretory granules in the unstimulated goblet cells were mostly round and small, and separate from each other. It is concluded that the ultrastructure of secretory granules is artefactually modified by conventional fixation methods and that granule structure in goblet cells alters during the secretory process.