In consequence of right-sided smpathectomy at the level of C5 it was found that in the sheep the cervical sympathetic trunk contains nerve fibres which proceed from cells situated in the first four segments of the thoracic part of the spinal cord and in the stellate ganglion. These fibres are about 85 per cent of all fibres of the sympathetic trunk. The remaining 15 per cent proceed from nerve cells situated nasally of the anterior cervical ganglion.
The spinal cord. Changes found in the segment Th1 – Th4 in sheep III and IV closely resembled those
seen in the stellate ganglion (Figures 6, 7).
2. After severing the sympathetic trunk, the cells of its origin undergo complete disintegration within
a year.
3. After severing the cervical sympathetic trunk, the cells of the cervical sympathetic ganglion
undergo transneuronic degeneration.
http://onlinelibrary.wiley.com/doi/10.1111/j.1439-0442.1967.tb00255.x/abstract