Location of retrograde changes in the nervous system following unilateral lympathectomy in sheep.

The present paper is a continuation of our studies on the location of retrograde changes in the nervous system following unilateral sympathectomy in sheep (5). Our previous investigations showed that a majority (85%) of the fibres of the cervical sympathetic trunk run towards the anterior cervical ganglion, and about 15% of the fibres proceed from nerve cells situated nasal to the same ganglion. The available literature does not offer a full explanation of this fact. Some authors (3, 7) are of the opinion that the anterior cervical ganglion is joined by the fibres proceeding from the IX, X and XII nerve. The opponents of this opinion regard these fibres as sensory (1, 2, 4) or sympathetic (6). The objective of the present work was to obtain at least a partial elucidation of this question in sheep. We thought it also of interest to study transneuronic degeneration in the sympathetic system and the behaviour of the cells of origin of the sympathetic trunk after a longer time following sympathectomy.