The bovine tubouterine junction: general innervation pattern and distribution of adrenergic, cholinergic, and peptidergic nerve fibers.

The innervation of the bovine tubouterine junction was studied in sexually mature heifers using antisera against various neuronal markers and a modified acetylcholinesterase method. The vast majority of the nerve fibres in the bovine tubouterine junction belongs to the sympathetic nervous system; peptidergic and cholinergic fibers are restricted to characteristic locations. The endosalpinx in the adovarian portion of the terminal tubal segment is poorly innervated. The mucosa of the aduterine portion and of the tubouterine transitional region proper receives a strikingly dense innervation, which is observed mainly in combination with a strong vascularisation of specialised mucosal structures. In the endometrium, perivascular nerves accompany the ascending spiral arteries but sporadic contacts between nerve fibres and uterine glands are also observed. From the muscular coat the inner longitudinal layer of the terminal tubal segment is more richly supplied by nerve fibres than the intermediate circular and outer longitudinal layers of the tubouterine junction. No changes in the innervation pattern were seen during the different stages of the sexual cycle.