Scanning electron-microscopic studies on protein plugs obtained from patients with chronic pancreatitis.

The previous histochemical study on the endoscopically obtained protein plugs revealed the process of protein plug formation. The present scanning electron-microscopic study was performed to clarify the fine structure of the protein plug and was quite in accordance with the results of the histochemical study: (1) protein plugs were constructed of interlacing networks and amorphous material stuffed in the networks; (2) protein plug formation started in the form of random and loose interlacing of cottony network fibrils and poor stuffing with degenerating epithelial cells and amorphous material, and in this stage protein plugs enlarged by adherence of smaller aggregates; (3) with maturation, protein plugs came to be covered by stratiform fine net works which were more compactly built up with uniformly thick, dense and smooth fibers and were stuffed more densely with amorphous material; (4) mature protein plugs were considered to enlarge by repeated process of stratiform deposit of reticular substance and amorphous material and subsequent maturation. However, it remains to be clarified which factors induce the changes of networks from random interlacing to stratiform arrangement.