A light- and electron microscopic study of tyrosine hydroxylase-like immunoreactivity in the ciliary ganglia of monkey (Macaca fascicularis) and cat.

The present paper describes tyrosine hydroxylase-like immunoreactivity in the ciliary ganglion of monkey (Macaca fascicularis) and cat. Under the light microscope, in the monkey, about 7.6% of neurons were observed to be intensely stained, 27.7% moderately stained and 32.5% lightly stained. In the cat, 1.2% of neurons were intensely stained, 5.4% moderately stained and 10.1% lightly stained. Ultrastructurally, tyrosine hydroxylase-like immunoreactivity was observed in neuronal somata, dendritic profiles and axons in both monkey and cat. Tyrosine hydroxylase-like immunoreactive dendritic profiles were synaptically contacted by tyrosine hydroxylase-negative axon terminals. In the monkey, tyrosine hydroxylase-like immunoreactive fibres were observed to enter the ciliary ganglion via the nasociliary nerve. Such fibres were observed to course among neurons within the ganglion and emerge in the short ciliary nerves. In contrast, tyrosine hydroxylase-like immunoreactive fibres were only occasionally observed in the cat.