Collagen is further packed into fibrillar collagen types with hexagional or quasi hexagonal shapes. The packing may be 'sheet-like' or microfibrillar. The microfibrillar structure of collagen fibrils in tendon, cornea and cartilage has been directly imaged by electron microscopy.
The microfibrillar structure of adult tendon was confirmed in 2006 by Fraser, Miller and Wess (amongst others). They found the D-periodic pentameric arrangement and termed it microfibril.