Contribution of cryotechniques to the study of elastin ultrastructure

Cryomethods were used in order to investigate the ultrastructure of native elastin fibres from beef ligamentum nuchae. Filaments of diameter 5 nm, running almost in parallel in purified, negatively-stained elastin preparations, were also seen running along the elastin fibre both in freeze-fractured and etched elastin, that had been stretched up to 200%, and in cryo-sectioned elastin that had been stretched and chemically fixed before freezing. Interconnections between elastin filaments were revealed by the freeze-etching technique. Glycerol treatment, which probably leads to hydration of specimens, resulted, however, in disorganization of filaments and swelling of the elastin fibre. In conclusion, by the use of cryotechniques, it was convincingly demonstrated that elastin molecules are arranged in long interconnecting filaments of about 4-5 nm width.