Autonomic nerve tumour with skeinoid fibres: ultrastructure of skeinoid fibres examined by quick-freezing and deep-etching method

A case of gastrointestinal autonomic nerve tumour with skeinoid fibres (SFs ) of the jejunum in a 79-year-old Japanese man, was examined by the quick-f reezing and deep-etching (QF-DE) method. The tumour consisted of spindle ce lls with immunohistochemical reactions for vimentin, NSE and CD34. Electron microscopically, features of the neural cells of the myenteric plexus were observed. The OF-DE method demonstrated intercellular meshwork structures, consisting of thin filaments (7-15 nm), with granular deposits. Fully deve loped parts of the deposits formed nodular aggregates composed of irregular ly surfaced thick fibrils (30-48 nm) with a tendency to linear arrangement (SFs). We detected many interconnecting thin filaments (ICTFs) between the SFs, which were pre-existing components in the meshwork, avoiding the granu lar deposits. The focal thickening formed by the connection between SFs and ICTFs revealed a periodicity typical of SFs (33-45 nm). We conclude that S Fs are formed by decoration of the granular deposits along pre-existing int ercellular meshwork structures.