The similarity of the ultrastructural changes in the light pinealocytes occurring after sympathectomy and after continuous illumination was striking. It is supposed that these changes have a common cause,viz. the lack of free noradrenaline, the pinealotropic neurotransmitter.
Journal of Neural Transmission Volume 36, Numbers 3-4 / September, 1975
http://www.springerlink.com/content/j121443576128248/