New Anatomical Analyses Suggest a Pumping Mechanism for the Vomeronasal Organ in Anurans

Based on histological cross-sections of the frog Phrynohyas resinifictrix, we present evidence suggesting the presence of a pumping mechanism associated with the function of the vomeronasal organ. We also propose that the fluid supply for the mechanism originates from gland secretions, which may also play a role in providing the vomeronasal organ with chemical cues.

Fig. 1

Three-dimensional reconstruction of the nasal cavity of Phrynohyas resinifictrix. (A) Frontal view of the right cavity. (B) The nasal cavities projected into a schematic representation of the frog's head. (C) Ventral view of the VNO and the isthmus. Note the separated position of the vomeronasal chamber.

Fig. 2

Schematic representation of a series of cross sections of the nasal region of Phrynohyas resinifictrix. Dark grey = normal olfactory epithelium; hatched dark grey = vomeronasal olfactory epithelium; stippling = cartilage; black = bone.

Fig. 3

Cross section of the nose of Phrynohyas resinifictrix. The left isthmus is closed by two rows of dilated vessels, while the right isthmus is open because the vessels are constricted. Scale bar = 290 µm.

Fig. 4

Magnified sections of the framed parts of Figure 3. Scale bar = 85 µm. (A) Left side. (B) Right side.

Fig. 5

Cross section of the nasal cavity of Phrynohyas resinifictrix showing the two main nasal glands and the ductus nasolacrimalis. Scale bar = 170 µm.

Contributor Notes

Associate Editor: D. Kizirian.

¹ Abteilung für Zoologie/Entwicklungsbiologie, Institut für Biologie, Universität Kassel, Heinrich-Plett-Str. 40, D-34109 Kassel, Deutschland; E-mail: (CN) nowack@uni-kassel.de; and (AWR) woehrep@uni-kassel.de. Send reprint requests to this address.

Received: 15 Nov 2007

Accepted: 06 Jun 2008