The nervous control of intraluminal pressure in the vomeronasal organ of the domestic ram.

In order to examine whether an aspiration mechanism exists in the vomeronasal organ (VNO) of the domestic ram, experiments were conducted in chloralose-anaesthetized animals using acute electromanometry and electrophysiological techniques. Stimulation of the ipsilateral cervical sympathetic nerve activated a mechanism producing a negative (with respect to atmospheric pressure) intraluminal pressure which drew fluid into the VNO from the nasopalatine canal. The mechanism was under alpha-adrenergic control and did not seem to involve the carotid blood supply. An ipsilateral increase in intraluminal pressure occurred following electrical excitation of the maxillary trigeminal innervation. Thus a mechanism was demonstrated in the ram for conveying odours to the putative olfactory receptors in the VNO.