Larval development and metamorphosis of the olfactory and vomeronasal organs in the toad Rhinella (Bufo) arenarum (Hensel, 1867)

Abstract

Jungblut, L.D., Pozzi, A.G. and Paz, D.A. 2011. Larval development and metamorphosis of the olfactory and vomeronasal organs in the toad Rhinella (Bufo) arenarum (Hensel, 1867). -Acta Zoologica (Stockholm) 92: 305-315.The olfactory and the vomeronasal system are the two major chemosensory systems found in terrestrial vertebrates. Among tetrapods, amphibians are unique in having an aquatic larval stage, followed by metamorphosis to a terrestrial adult. In the present work, we studied the histological development of the olfactory and vomeronasal organ and associated multicellular glands of the toad Rhinella (Bufo) arenarum, from early poshatching larva to postmetamorphic toadlets. As in other bufonids, the olfactory epithelium of R. arenarum in larvae is divided into dorsal and ventral branches in the rostral and mid-nasal regions. At metamorphic climax, the larval pattern changes drastically and the adult olfactory configuration develops. Bowman's glands appear in the olfactory epithelium of R. arenarum at the onset of metamorphic climax. The vomeronasal epithelium develops early in larval development in R. arenarum, around the time of operculum development. Interestingly, a novel sensory epithelium develops in the floor of the principal chamber of R. arenarum at metamorphic climax. This novel sensory epithelium resembles larval sensory epithelium lacking Bowman's glands, and suggests that these animals would be able to sense not only air-borne, but also water-borne odors during their adult terrestrial life.

Ontogenetic Development of the Derived Olfactory System of the Mantellid Frog Mantidactylus betsileanus

“…Furthermore, our results provide evidence for an emergence of this anatomical state only at the very end of metamorphosis. Up to that point, the development of the olfactory system in M. betsileanus largely corresponds to that of other anuran species with indirect development as described by several authors (Watanabe, : Rhacophorus schlegelii ; Rowedder, : Alytes obstetricans , Bufo bufo ; Jermakovicz et al, : Anaxyrus americanus ; Jungblut et al, : Rhinella arenarum ; Královec et al, : Discoglossus pictus ). As in all these species, the two olfactory organs (MOO and VNO) develop during the larval period, prior to metamorphosis.…”

The ontogeny of the olfactory system in ceratophryid frogs (Anura, Ceratophryidae)

“…In Chacophrys, a part of the ventral olfactory epithelium is exposed to the oral cavity at the anterior border of the choana (the "buccal exposed olfactory epithelium" of Jungblut et al, 2017). This is a feature that appears sporadically in a variety of anuran larvae (Benzekri & Reiss, 2012;Jermakowicz et al, 2004;Jungblut et al, 2011Jungblut et al, , 2012Jungblut et al, , 2017Khalil, 1978;Rowedder, 1937;Tsui, 1946;Wassersug, 1980;Yvroud, 1966), and has been suggested to function as a chemosensory detector for sampling of oral cues during the larval period, complementing the role of taste buds (Jungblut et al, 2017;Wassersug, 1980). It is of interest that only the microphagous ceratophryid shows this feature.…”

“…The vomeronasal organ opens into the dorsomedial part of the anterior principal cavity; it consists of a sensory epithelium of variable thickness among species. This general morphology of the nose is found in a wide variety of anuran larvae (Jermakowicz et al, ; Jungblut, Pozzi, & Paz, ; Jungblut, Reiss, Paz, & Pozzi, ; Khalil, ; Rowedder, ; Tsui, ; Watanabe, ; Yvroud, ), although notable deviations are found in the ascaphid Ascaphus truei (Benzekri & Reiss, ; Pusey, ), the pipid Xenopus laevis (Föske, ; Paterson, ), and the microhylid Kaloula borealis (Tsui & Pan, ).…”

“…This general morphology of the nose is found in a wide variety of anuran larvae (Jermakowicz et al, 2004;Jungblut, Pozzi, & Paz, 2011Jungblut, Reiss, Paz, & Pozzi, 2017;Khalil, 1978;Rowedder, 1937;Tsui, 1946;Watanabe, 1936;Yvroud, 1966), although notable deviations are found in the ascaphid Ascaphus truei (Benzekri & Reiss, 2012;Pusey, 1943), the pipid Xenopus laevis (F€ oske, 1934;Paterson, 1939), and the microhylid Kaloula borealis (Tsui & Pan, 1946).…”

Integração morfológica e modularidade em crânios das espécies do grupo Rhinella granulosa

“…A mechanistic connection between the adult toad skull and precipitation patterns can be made, especially for snout bones. The snout region protects and supports the olfactory epithelium, which has a role in the detection of water cues in adult toads (Jungblunt et al 2011). The species from the R. granulosa group are explosive breeders dependent on ephemeral pools to reproduce , and the ability to detect sites for reproduction is probably fundamental to population persistence.…”