Salamander vomeronasal

Salamander vomeronasal systems why plethodontids smell well. American Zoologist 27,166A. 

Correlation of salamander vomeronasal and main olfactory system anatomy with habitat and sex behavioral interpretations. In Chemical Signals in Vertebrates, vol. 6, ed. R. L. Doty and D. Miiller-Schwarze, pp. 403-409. New York Plenum. 

In its central projections the vomeronasal pathway, distinguished by a unique lectin-affinity, ascends to an accessory olfactory bulb, while dorsal and ventral pathways supply the dorsal and ventral regions of the main olfactory bulb (Saito and Taniguchi, 2000). The AOS (but not the MOS) of salamanders displays considerable diversity in the... 

Fig. 2.7 Salamander nasal cavity TS — anterior to entry of naso-lacrimal duct. LD = lateral diverticulum NSE = non-sensory epithelium VNE = vomeronasal epithelium MOE = olfactory epithelium and RP = reflective pigment (after Dawley, 1988).

Temporal alterations in peripheral chemoreceptors are rare in vertebrates, but this group provides an example of transient enhancement of signal capture efficiency. The Red-backed salamander (Plethodon cinereus) shows dimorphic and seasonal VNO volume fluctuations. Males always possess a significantly larger vomeronasal area, and both... 

Eisthen H.L. (2000a). Presence of the vomeronasal system in aquatic salamanders. Philos Trans Roy Soc Lond B 355, 1209-1213. 

Schmidt A. and Roth G. (1990). Central olfactory and vomeronasal pathways in salamanders. J Himforsch 31, 543-553. 

Schmidt A., Naujoks-Manteuffel C. and Roth G. (1988). Olfactory and vomeronasal projections and the pathway of the Nervus terminalis in ten species of salamanders — a whole mount study employing the horseradish-peroxidase technique. Cell Tissue Res 251, 45-50. 

The delivery of male courtship pheromones is widespread among plethodontid salamanders (Houck and Arnold 2003), and other courtship pheromones are being discovered for this group (Houck, Palmer, Watts, Arnold, Feldhoff and Feldhoff 2007). The mode by which these pheromones are transferred to the female apparently has been modified from delivery via diffusion into the circulatory system to delivery that directly stimulates vomeronasal receptors (Fig. 20.1 Houck and Sever 1994 Watts et al. 2004 Palmer et al. 2005 Palmer et al. 2007). The behavior patterns and morphologies associated with these two delivery modes often remain static for millions of years. In contrast, evolution at the level of pheromone signals is apparently an incessant process that continuously alters the protein sequence and composition of pheromones both within and among species (Watts et al. 2004 Palmer et al. 2005 Palmer et al. 2007). 

The terrestrial salamander Plethodonjordani applies courtship pheromone to the female hy ruhhing or slapping his mental gland directly on the female s nares. This way the pheromone can stimulate the vomeronasal organ and accessory olfactory system. Experimental application of mental gland extracts to the nares of females accelerated the time until active courtship started (Houck etal., 1998). 

Placyk, J. S. and Graves, B. M. (2002). Prey detection by vomeronasal chemoreception in a plethodontid salamander. JoarnflZo/C/iem/cflZEcoZo 28,1017-1036. 

Mason, J. R., Meredith, M., 8c Stevens, D. A. 1981. "Odorant Discrimination by Tiger Salamanders After Combined Olfactory and Vomeronasal Nerve Cuts." Physiology and Behavior, 27 125-132. 

Dawley, E. M., 1992, Sexual dimorphism in a chemosensory system the role of the vomeronasal organ in salamander reproductive behavior, Copeia 1992(1) 13-120. 

In axolotls, as in most other salamanders, the vomeronasal organ consists of a pouch that protrudes from the lateral edge of the nasal cavity (Figure 1). The vomeronasal organ... 

Figure 2. Schematic diagram of the nasal cavities and forebrain of a salamander, illustrating the central projections of the olfactory and vomeronasal systems in dorsal view. Anterior is toward the top of the figure, and only ipsilateral projections are shown. The medial (A) and lateral (B) olfactory tracts arise from the olfactory bulb. (C) The extra-bulbar ol ctory pathway bypasses the olfactory bulb and projects directly to the anterior preoptic area. (D) The accessory olfactory bulb, which receives input from the vomeronasal organ, projects to the lateral amygdala (la). Other abbreviations apoa = anterior preoptic area dp = dorsal pallium Ip = lateral pallium mp = medial pallium ma = medial amygdala s = septum sir = striatum. Based on descriptions in Hetrick, 1927,1933,1948 Kokoros and Northcutt, 1977 and Schmidt and Roth, 1990.

Wirsig-Wiechmann, C. R., Houck, L. D., Feldhoff, P. W., and FeldhofL R. C., 2002, Pheromonal activation of vomeronasal neurons in plethodontid salamanders. Brain Res. 952 335-344. 

Dawley, E. M., and Crowder J., 1995, Sexual and seasonal differences in the vomeronasal epithelium of the red-backed salamander (Plethodon cinereus), J. Comp. Neurol. 359 382-390. 

Figure 2. Comparison of total chemosensory epithelial volume (olfactory plus vomeronasal) plotted against total body lengths (minus the tail) for white-footed mice, short-tailed shrews, and Plethodontid salamanders. Whitefooted mice are represented by open circles with dot, short-tailed shrews by open squares, and salamanders by filled circles Desmognathns wrighti), filled triangles Desmognathus quadramaculatus), and filled diamonds Plethodon glutinosus).

For further comparison, we included data points (again, combined olfactory and vomeronasal volume, equaling a total chemosensory epithelial volume) for three species of closely related, mainly terrestrial salamanders (family Plethodontidae). Salamanders have no turbinates and the chemosensory epithelium of terrestrial species is arranged in flat sheets. Not surprisingly, chemoreceptor epithelial volume is considerably less in salamanders than in mammals (ANOVA of multiple regression, P =0.0001). In addition, the slope for the salamander line is considerably flatter than for white-footed mice, but not for short-tailed shrews, indicating less variation in chemosensory epithelial volume that is explained by variation in body size. 

Dawley, E.M. Bass, A.H. 1989. Chemical access to the vomeronasal organs of a plethodontid salamander. J. 

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