Neuronal projections to the medial preoptic area of the sheep, with special reference to monoaminergic afferents: Immunohistochemical and retrograde tract tracing studies

The preoptic area contains most of the luteinizing hormone releasing hormone immunoreactive neurons and numerous monoaminergic afferents whose cell origins are unknown in sheep. Using tract tracing methods with a specific retrograde fluorescent tracer, fluorogold, we examined the cells of origin of afferents to the medial preoptic area in sheep. Among the retrogradely labeled neurons, immunohistochemistry for tyrosine hydroxylase, dopamine‐β‐hydroxylase, phenylethanolamine N‐methyltransferase, and serotonin was used to characterize catecholamine and serotonin fluorogold labeled neurons.