Elastic fibres of periodontal ligament which regulate the vascular flow:
Periodontal ligament consists of principal fibres and elastic fibres. Principal fibres are made up of collagen type I. They are purely collagenous.
The elastic fibres are present in two immature forms called oxytalan and elaunin (AIIMS-07). Oxytalan fibres run parallel to the root surface and are attached to the blood vessels thus they regulate the vascular flow.
Oxytalan
Elaunin
Both
Elastin