The ultrastructure of elastic elements and other extracellular substances was examined in experimental intimal thickening produced under conditions described in the first part of this series. It seems that the precursor of the elastic fibers is produced by the young smooth muscle cells constituting the intimal thickening. The precursor, which may be identical with desmosin, acquires further components from mucopolysaccharide filaments of the basement membrane and forms the elastic granules of 70-Å diameter. In the extracellular space the elastic granules unite to form elastic fibrils of 140-Å periodicity, which partly by linking with each other, partly by embedding in mucopolysaccharide, give rise to elastic clumps of 0.04 - 0.2-μ diameter. Finally, the elastic fibers arise by fusion of the elastic clumps. The basement membrane of the smooth muscle cells seems to have a close relationship with elastic fiber formation. The dissimilar PTA-binding ability of the various elastic elements has been a matter of controversy in the literature; the hypothetical explanation offered in this study remains to be confirmed.
ASJC Scopus subject areas
- Pathology and Forensic Medicine
- Molecular Biology
- Clinical Biochemistry