ABSTRACT
The mechanisms to obtain and store skin toxins in frogs in of the family Dendrobatidae are not completely understood. In order to contribute to understand how toxins are stored, we provide a histological description of the cutaneous glands of the species Phyllobates bicolor. The skin of two adult frogs was examined through three histological staining techniques (hematoxilin-eosin, PAS and Masson Trichrome) using conventional optic microscopy. The skin of Phyllobates bicolor contains two types of exocrine glands: mucous and serous, which empty their products to the epidermal surface through an intra-epithelial duct that leads to a stoma. The mucous and serous glands and the intercalated ducts are surrounded by a discontinuous sheath of myoepithelial cells, which colapse the lumen of the acinus and the lumen of ducts and facilitate the secretion and release of their content. The serous glands have a polarized syncytium of tall cuboidal or columnar epithelial cells. Both glands have a mixed secretion, thus, the contents of mucous glands tend to be neutral and basophilic, while the contents of the serous glands are basophilic and acidophilic.
A la fecha no existe mayor información con respecto a los mecanismos para obtener y almacenar las toxinas cutáneas de ranas de la familia Dendrobatidae. Con el fin de contribuir y entender cómo son almacenadas estas toxinas, realizamos una descripción histológica de las glándulas cutáneas de la especie Phyllobates bicolor. La piel de dos ranas adultas se examinó mediante tres técnicas de tinción histológica (hematoxilina-eosina, PAS y tricrómico de Masson) mediante microscopía óptica convencional. La piel de P. bicolor contiene dos tipos de glándulas exocrinas: mucosas y serosas, que vierten sus productos a la superficie epidérmica a través de un conducto intra-epitelial que conduce a un estoma. Las glándulas mucosas, serosas y los conductos intercalados están rodeados por una funda discontinua de células mioepiteliales, las que colapsan el lumen de los acinos y conductos, facilitando la secreción y liberación de su contenido. Las glándulas serosas tienen un sincitio polarizado de células epiteliales columnares cúbicas. Ambas glándulas tienen una secreción mixta, por lo tanto, los contenidos de las glándulas mucosas tienden a ser neutral y basófilas, mientras que los contenidos de las glándulas serosas son basófilas y acidófilas.
Subject(s)
Animals , Anura/anatomy & histology , Poisons/metabolism , Skin/ultrastructure , Exocrine Glands/ultrastructure , Staining and Labeling/methods , Dermis/ultrastructure , Epidermis/ultrastructure , MicroscopyABSTRACT
The mucous glands (sublingual gland, pyloric gland, main pancreatic duct gland, duodenum gland and large intestinal gland) have been studied-by means of labelled lectins and histochemical methods. The results indicated that a large amount of mucopolysaccharide with sailic acid are found in sublingual glands and pyloric glands, while a large amount of sulfate mucopolysaccharide are observed in the other three glands. In addition, the reactivity of DBA and PNA in mucous glands are different, for example, the sublingual and large intestinal glands are negative for DBA and PNA staining. On the contrary, the pyloric glands, duodenum glands as well as main pancreatic duct glands are heavily stained with DBA, but various between the mucous glands stained with PNA. The goblet cells in duodenum, large intestine and main pancreatic duct are similar in their morphology, but the reactions of PAS, AB and lectins are different between them, even so in the same organ, the staining pattern also differ from their locations. The mucous glands and goblet cells contained different mucopolysaccharides, which might be concerr/ed with different functions in different organs.