The ultrastructure of elastin revealed by freeze-fracture electron microscopy

The ultrastructural organization of the elastin from beef ligamentum nuchae has been investigated by comparing fracture surfaces of stretched and relaxed specimens. When fractured both parallel and transverse to the fibre, unstretched elastin appears as a disordered granular material. In stretched material a filamentous organization in relation to the applied force becomes evident. The filamentous organization becomes more pronounced as the elongation of the fibre increases. Stretching by 180–200% produces filaments of about 5nm across which exhibit subunits along their long axes. It is concluded that elastin is organized as globules of about 5nm across arranged in long filaments which form a three-dimensional network and only become visible after stretching.