Sublingual plicae (anterior processes) are not necessary for garter snake vomeronasal function.

Abstract

The anterior processes of snakes may transfer odorants from the tongue to the vomeronasal (VN) organ. To test whether the anterior processes are required for a vomeronasally mediated behavior, the authors tested garter snakes (Thamnophis sirtalis) preoperatively and after cauterization of the anterior processes or control cauterization with artificial earthworms covered with earthworm wash (EWW) or distilled water. Snakes in both groups attacked EWW-covered artificial worms but not controls both pre- and postoperatively. In addition, snakes with anterior processes cauterization or control cauterization tongue flicked 3H-proline. Radioautographs of the VN organs of snakes with and without anterior processes were indistinguishable: Snakes in both groups had reduced silver grains over the VN sensory epithelium as had been reported previously with intact snakes. These findings indicate that the anterior processes are unnecessary both for a behavior known to require a functional VN system and for delivery of odorants to the VN organ.

The forked tongue and edge detection in snakes (Crotalus oreganus): An experimental test.

“…The tongue then transfers its chemicals to the vomeronasal system via blind-ended ducts leading to each VNO (Gillingham & Clark, 1981; Young, 1990). The tongue tines may deliver their chemicals to the paired plicae in the floor of the mouth, but destruction of the plicae does not significantly impair transfer of odors to the VNO from the tongue, suggesting that the plicae may not be important in maintaining lateralization of this system (Halpern & Borghjid, 1997). Chemical cues in the lumen of the VNO bind to the sensory epithelial receptor cells of the VNS (Jiang et al, 1990), and the axons of the receptor cells bundle together to form the vomeronasal nerve (VNN).…”

Structural and Functional Characterization of the Tongue and Digestive Tract ofPsammophis sibilans(Squamata, Lamprophiidae): Adaptive Strategies for Foraging and Feeding Behaviors

“…Previous studies documented that the lingual plicae receive chemical cues and odorant molecules from the tongue tines; however, others stated that the destruction or removal of these plicae did not remarkably impair odor transfer to the VNO (Mcdowell, 1972; Mao et al, 1991; Parker et al, 2008). It was hence plausible that lingual plicae are not necessary to maintain the lateralization of the VNO system (Halpern & Borghjid, 1997). Concurrently, Mcdowell (1972) emphasized that the conspicuous median ventral ridge, the median tubercle, confers a steering pressure against the lingual tines during protrusion and retraction as well as bounding the sublingual gland orifices that mainly secrete mucous; lubricating the lingual tips as evidenced by our SEM imagery (Gillingham & Clark, 1981).…”

Snakes: Slithering from Sensory Physiology to Cognition

“…Gillingham and Clark (1981) suggested that the elevation of the anterior processes of sublingual plicae may be responsible for the transfer of chemicals, as they might promote creation of the vacuum in the VNO. However, more recent research failed to confirm their role in it (Halpern & Borghjid, 1997). So the exact mechanism of the transfer of chemicals from tongue to the VNO remains unknown.…”