Location of sympathetic postganglionic and sensory neurons innervating thetestis in the male chicken

Sympathetic postganglionic and sensory neurons were labelled by injections of horseradish peroxidase into the testis of the male chicken. The total nu mber of labelled neurons in the paravertebral, prevertebral, dorsal root an d nodose ganglia was 943 on average for five chickens. Sympathetic postgang lionic neurons were located in the paravertebral ganglia T3-LS3 (10 % of th e total number of labelled neurons), especially in T6 and T7, and in the pr evertebral ganglia adjacent to the adrenal glands and aorta (19 %). They we re found almost ipsilaterally. No labelled neurons were observed in the dor sal motor nucleus of the vagus. Sensory neurons were found bilaterally in t he dorsal root ganglia T2-LS3 (71 %), especially in T5 to T7. Over a quarte r of labelled sensory neurons were located in the contralateral dorsal root ganglia. In the nodose ganglia, only a few labelled sensory neurons were o bserved (much less than 1 %). These results indicate that, unlike the ovary , the testis of the chicken tends to be innervated by ipsilaterally located sympathetic postganglionic and sensory neurons, with the sensory neurons b eing more numerous than the sympathetic postganglionic neurons.