Abstract
We performed histologic evaluation of the parotid glands of 10 (male and female) Rhinella schneideri. Animals were manually captured during nocturnal collections in Bom Jesus, Piaui, and euthanized by administering a lethal dose of anesthetic thiopental. The parotid glands were then collected and embedded in paraffin, and sectioned to 4 µm blocks using a manual rotary microtome. Considering the lack of general information concerning anatomical and histological conditions of Rhinella scheneideri, we sought to address key characteristics of macro glands found in the species with the goal of a better understanding of the operation of this type of defense mechanism. Histological analysis revealed the presence of macrogland alveoli with ducts encircled with differentiated mucous cells, known as accessory glands, as well as granular glands. We also discovered glandular ducts on the glands which communicate with the outside of the body. These ducts are internally lined by duct glandular epithelial cells, forming a plug which promotes total obstruction of the duct. There were no histological differences in macro gland anatomy in this species compared to other species in Bufonidae.
Highlights
Μm blocks using a manual rotary microtome
Considering the lack of general information concerning anatomical and histological conditions of Rhinella scheneideri, we sought to address key characteristics of macro glands found in the species with the goal of a better understanding of the operation of this type of defense mechanism
Histological analysis revealed the presence of macrogland alveoli with ducts encircled with differentiated mucous cells, known as “accessory glands”, as well as granular glands
Summary
Foram coletados dez exemplares (dentre estes machos e fêmeas) da espécie Rhinella schneideri, capturados manualmente por coletas noturnas na cidade de Bom Jesus, Piauí, Brasil (9°4’19.04”S/ 44°21’5.54”O). Após a eutanásia dos animais, foram coletados fragmentos das glândulas parotoides ixados em solução aquosa de formaldeído tamponada a 10% com pH 7,0, permanecendo nesta solução por 72 horas. Macroscopicamente pode-se observar que as glândulas parotoides de Rhinella schneideri localizam-se caudalmente ao tímpano e dorsolateralmente a escápula (Figura 1). Ambos os tipos glandulares se conectam com o exterior através de ductos epidérmicos por onde a secreção é liberada na superfície corporal e são envolvidos por uma monocamada de células mioepiteliais, que é mais desenvolvida nas glândulas granulosas. Cada unidade secretora da parotoide possui um da epiderme envolta na camada esponjosa da derme, ducto que comunica o corpo glandular com o exterior. Esse ducto é revestido por células epiteliais glandulares meio externo que transpassam a derme (Figura 3). Essas células são caracterizadas por secretoras em forma de prisma, e encontram-se dispostas núcleos alongados semelhantes às células musculares ao redor do ducto alveolar e imediatamente abaixo lisas (Figura 2D)
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