Morphological Changes in Skin Glands During Development in Rhinella Arenarum (Anura: Bufonidae)

Abstract

Avoiding predation is critical to survival of animals; chemical defenses represent a common strategy among amphibians. In this study, we examined histologically the morphology of skin glands and types of secretions related to chemical skin defense during ontogeny of Rhinella arenarum. Prior to metamorphic climax the epidermis contains typical bufonid giant cells producing a mucous substance supposedly involved in triggering a flight reaction of the tadpole school. An apical layer of alcianophilic mucus covers the epidermis, which could produce the unpleasant taste of bufonid tadpoles. Giant cells disappear by onset of metamorphic climax, when multicellular glands start developing, but the apical mucous layer remains. By the end of climax, neither the granular glands of the dorsum nor the parotoid regions are completely developed. Conversely, by the end of metamorphosis the mucous glands are partially developed and secrete mucus. Adults have at least three types of granular glands, which we designate type A (acidophilic), type B (basophilic) and ventral (mucous). Polymorphic granular glands distribute differently in the body: dorsal granular glands between warts and in the periphery of parotoids contain protein; granular glands of big warts and in the central region of parotoids contain catecholamines, lipids, and glycoconjugates, whereas ventral granular glands produce acidic glycoconjugates. Mucous glands produce both mucus and proteins. Results suggest that in early juveniles the chemical skin defense mechanisms are not functional. Topographical differences in adult skin secretions suggest that granular glands from the big warts in the skin produce similar toxins to the parotoid glands. Anat Rec, 299:141-156, 2016. V C 2015 Wiley Periodicals, Inc.

Morphological and biochemical characterization of the cutaneous poison glands in toads (Rhinella marina group) from different environments

“…In the species here studied, the parotoids present a general morphology much similar to that described for all other species of Rhinella marina group [ 3 , 5 , 6 , 22 ]: they are basically composed of very elongated poison glands that decrease in diameter from the macroglandular centre towards the periphery (Fig. 2 d).…”

Prenatal hyperandrogenism induces alterations that affect liver lipid metabolism

“…The intestine of tadpole was used as a positive control of the SUDAN IV technique (Regueira et al 2016). To evaluate the TG content in the liver, 15 frozen samples of each group were saponified and TG content was quantified by comparing with a glycerol standard curve by using a commercial kit (Wiener Lab, Argentina), as described previously (Chow et al 2011).…”

Tadpoles of Rhinella schneideri as reservoirs of trichodinids in continental aquaculture

“…The relative disease resistance of the tadpoles may be linked to other factors such as different protection structures of their skin including the mucus components, the immune system of the species, or even as a result of an adaptation between the host and the parasite. The tadpoles also present an expressive mucous secretion on the body surface (Regueira et al, 2016). The presence of this mucus and resultant viscosity may reduce the contact of the parasites with the tegument, reducing damage even in heavy infestations.…”