Histological Study of Glandular Variability in the Skin of the Natterjack Toad—Epidalea calamita (Laurenti, 1768)—Used in Spanish Historical Ethnoveterinary Medicine and Ethnomedicine

Abstract

Common toads have been used since ancient times for remedies and thus constitute excellent biological material for pharmacological and natural product research. According to the results of a previous analysis of the therapeutic use of amphibians in Spain, we decided to carry out a histological study that provides a complementary view of their ethnopharmacology, through the natterjack toad (Epidalea calamita). This species possesses a characteristic integument, where the parotoid glands stand out, and it has been used in different ethnoveterinary and ethnomedical practices. This histological study of their glandular variability allow us to understand the stages through which the animal synthesises and stores a heterogeneous glandular content according to the areas of the body and the functional moment of the glands. To study tegumentary cytology, a high-resolution, plastic embedding, semi-thin (1 micron) section method was applied. Up to 20 skin patches sampled from the dorsal and ventral sides were processed from the two adult specimens collected, which were roadkill. Serous/venom glands display a genetic and biochemical complexity, leading to a cocktail that remains stored (and perhaps changes over time) until extrusion, but mucous glands, working continuously to produce a surface protection layer, also produce a set of active protein (and other) substances that dissolve into mucous material, making a biologically active covering. This study provides a better understanding of the use of traditional remedies in ethnoveterinary medicine.

Traditional Knowledge and Biocultural Heritage about Medicinal Plants in a European Transboundary Area (La Raya: Extremadura, Spain—Alentejo, Portugal): Transdisciplinary Research for Curriculum Design in Health Sciences

“…Depending on the context and type of community, you can go out into the countryside directly or access knowledge in centers or homes for the elderly and then walk along trails, paths, and areas to recognize things for oneself. This would be modeled on the approaches taken in this study with a focus on medical, social, and cultural anthropology, or on ethnobiology [101][102][103][104]. Thus, students will be able to use interviews, preferably semi-structured, as they allow the use of questions of interest to the research and, at the same time, give a voice to the subjects, according to their own logic [101][102][103][104].…”

“…This would be modeled on the approaches taken in this study with a focus on medical, social, and cultural anthropology, or on ethnobiology [101][102][103][104]. Thus, students will be able to use interviews, preferably semi-structured, as they allow the use of questions of interest to the research and, at the same time, give a voice to the subjects, according to their own logic [101][102][103][104]. Direct and participant observation can also be carried out, seeking to capture in the actions of the subjects their traditional knowledge and practices, remembering a prolonged coexistence with the social actors, as foreseen in ethnographic research [101][102][103][104].…”

“…It is important that interviews are carried out in twos or threes, to avoid communication problems with community members (informants). A voice recorder could be used, if participants agree, or notes in a diary, if participants do not agree to recording their voices, or both instruments [101][102][103][104].…”