Collagen fibril forming in vitro

Transmission electron micrograph of a collagen fibril forming in vitro from a solution of purified typeII collagen. The new molecules are being added to the tip of the fibril at the top left hand corner of the picture. The bands across the fibril are formed by the way the individual collagen molecules align. There is a one quarter stagger between adjacent collagen molecules which generates the 65nm banding pattern. The background meshwork is composed of smaller filamentous assemblies of the collagen molecules.