ABSTRACT
The mammalian ovary has been known as receiving its innervation by sympathetic and sensory neurons of the peripheral nervous system from the brain. Recently, there were several functional reports that the vagus nerves were also regulating the ovarian function, but the vagus nerve had not been identified by clear morphological evidence. A viral transneuronal tracing technique has been used to demonstrate the morphological evidence for the central vagal involvement in ovarian innervation in brain areas. Bartha strain of pseudorabies virus injection was made into the ovary of Sprague Dawley rats. In experimental group, the vagus nerve of the same injection side was removed right after ovarian injection. At five days after initial injection, all the rats were sacrificed and brains were processed for immunohistochemistry. Several central nuclei including hypothalamic paraventricular nucleus showed strong bilateral positive labelings after unilateral injection in control rats, but the positive labelings were disappeared or decreased in several hypothalamic nuclei and nuclei of the vagus nerve. In conclusion, these results provide the morphological evidence that vagus nerve has neural connection to ovary and by which the central nervous system may maintains the state of ovulation and reproduction as a possible parasympathetic routes in mammals.