A QUANTITATIVE STUDY OF NUCLEUS OF MESENCEPHALIC TRACT OF TRIGEMINAL NERVE OF CAT

The number of cells in the mesencephalic nuclei of 38 cats averaged 2015 and ranged from 1237 to 2946. The individual right and left nuclei averaged 980 cells and ranged from 581 to 1489. About 3% of the cells were chromatolytic in the control animals. Various nerves were sectioned and the animals were sacrificed 14 days later. After unilateral section of the nerve to the masseter muscle 18% of the cells in the ipsi‐ and 9.7% of the cells in the contralateral nuclei were chromatolytic. After simultaneous unilateral section of the nerves to both the masseter and temporalis muscles 3% of the ipsi‐ and 23% of the cells of the contralateral nuclei were chromatolytic. After unilateral section of the inferior alveolar nerves 13% of the cells of the ipsi‐ and 9% of the cells of the contralateral nuclei were chromatolytic. After unilateral section of the lingual nerves 9% of the cells of the ipsi‐ and 7% of the cells of the contralateral nuclei were chromatolytic. After unilateral section of the hypoglossal nerves 12% of the ipsi‐ and 10% of the cells of the contralateral nuclei were chromatolytic. These results provide anatomical evidence that the axons of the cells of the mesencephalic nuclei are distributed to both the ipsi‐ and contralateral peripheral nerves. These findings also confirm the presence of such axons in the lingual and inferior alveolar nerves and demonstrate their heretofore unsuspected presence in the hypoglossal nerve. Copyright © 1969 Wiley‐Liss, Inc.