Development of the nasal chemosensory organs in two terrestrial anurans: The directly developing frog, Eleutherodactylus coqui (Anura: Leptodactylidae), and the metamorphosing toad, Bufo americanus (Anura: Bufonidae)
Article first published online: 18 JUN 2004
Copyright © 2004 Wiley-Liss, Inc.
Journal of Morphology
Volume 261, Issue 2, pages 225–248, August 2004
How to Cite
Jermakowicz, W. J., Dorsey, D. A., Brown, A. L., Wojciechowski, K., Giscombe, C. L., Graves, B. M., Summers, C. H. and Ten Eyck, G. R. (2004), Development of the nasal chemosensory organs in two terrestrial anurans: The directly developing frog, Eleutherodactylus coqui (Anura: Leptodactylidae), and the metamorphosing toad, Bufo americanus (Anura: Bufonidae). J. Morphol., 261: 225–248. doi: 10.1002/jmor.10246
- Issue published online: 18 JUN 2004
- Article first published online: 18 JUN 2004
- University of Southern Indiana
- Office of the Vice President for Research at The University of Michigan
- vomeronasal organ;
- olfactory organ;
- direct development;
Nearly all vertebrates possess an olfactory organ but the vomeronasal organ is a synapomorphy for tetrapods. Nevertheless, it has been lost in several groups of tetrapods, including aquatic and marine animals. The present study examines the development of the olfactory and vomeronasal organs in two terrestrial anurans that exhibit different developmental modes. This study compares the development of the olfactory and vomeronasal organs in metamorphic anurans that exhibit an aquatic larva (Bufo americanus) and directly developing anurans that have eliminated the tadpole (Eleutherodactylus coqui). The olfactory epithelium in larval B. americanus is divided into dorsal and ventral branches in the rostral and mid-nasal regions. The larval olfactory pattern in E. coqui has been eliminated. Ontogeny of the olfactory system in E. coqui embryos starts to vary substantially from the larval pattern around the time of operculum development, the temporal period when the larval stage is hypothesized to have been eliminated. The nasal anatomy of the two frogs does not appear morphologically similar until the late stages of embryogenesis in E. coqui and the terminal portion of metamorphosis in B. americanus. Both species and their respective developing offspring, aquatic tadpoles and terrestrial egg/embryos, possess a vomeronasal organ. The vomeronasal organ develops at mid-embryogenesis in E. coqui and during the middle of the larval period in B. americanus, which is relatively late for neobatrachians. Development of the vomeronasal organ in both frogs is linked to the developmental pattern of the olfactory system. This study supports the hypothesis that the most recent common ancestor of tetrapods possessed a vomeronasal organ and was aquatic, and that the vomeronasal organ was retained in the Amphibia, but lost in some other groups of tetrapods, including aquatic and marine animals. J Morphol. 261:225–248, 2004. © 2004 Wiley-Liss, Inc.