Flehmen and vomeronasal organ function in male goats.

The possible role of flehmen behavior in facilitating the passage of non-volatile materials from the oral cavity to the vomeronasal organ (VNO) was studied by the use of a tracer dye, sodium fluorescein. The dye was applied to the oral cavity of six male goats in which flehmen was elicited by the presentation of female urine. Immediately afterwards a lethal dosage of anesthetic was given and the maxilla, including the VNO, was removed, frozen, and cut into transverse sections. Seven control subjects were treated similarly but were not stimulated to display flehmen. Examination of transverse sections under ultraviolet illumination revealed dye in the posterior part of the VNO in most subjects that performed flehmen but only in the anterior part of the VNO of subjects that did not perform flehmen. Inasmuch as only the middle and posterior parts of the VNO contain sensory epithelium, it was concluded that, if the dye represented a behaviorally significant non-volatile material (sex attractant), only the goats that showed flehmen would have detected the material from VNO chemoreception.