Anatomical, morphological, histochemical and ultra structural study of Duvernoy´s gland of six species of opisthoglyphous colubrids (Serpentes - Colubridae - Xenodontinae) / Estudo anatômico, morfológico, histoquímico e ultra-estrutural da glândula de Duvernoy de seis espécies de colubrídeos opistóglifos (Serpentes - Colubridae - Xenodontinae)

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

The colubrids have often been responsible for severe accidents, sometimes fatal for humans, all over the world. In the Hospital Vital Brazil of the Institute Butantan, in São Paulo, 40% of the snakebite registered is caused by serpents that are considered no poisonous. Among these, 97.3% belong to Colubridae family with 54.5% presenting aglyphous dentition and 42.8%, opisthoglyphous dentition. However, some accidents that involve the opisthoglyphous colubrids can break out clinic manifestation similar to the botropic accident. This fact has caused many debates, because due to an erroneous diagnosis or to the gravity of the accident, very often it is administered the anti-botropic serum, which in many cases may be ineffective or even harmful for the patient. It is important to mention that rare are the studies related to the venon-delivery-system of the colubrids. Thus, we propose to study the anatomical, morphological, histochemical and ultra structural characteristics of the Duvernoy´s gland of six species of opisthoglyphous colubrids. They are Philodryas olfersii and Philodryas patagoniensis of Tribe Philodryadini, Oxyrhopus guibei and Phimophis guerrini of Tribe Pseudoboini and Thamnodynastes strigatus and Tomodon dorsatus of Tribe Tachymenini. The Duvernoy´s glands of the species in question were analyzed macroscopically for description of the anatomical characteristics. They were then fixed in Bouin´s liquid for posterior histological procedures for morphologic and histochemical analysis. For the ultra structural study, the Duvernoy´s glands were fixed in glutaraldehyde 2.0% in buffer cacodylate 1.0 M (pH 7.3) for further preparation according to the established protocol. The results showed that the above-mentioned gland presents two well distinct portions, the salivary supralabial gland and the Duvernoy´s gland itself, with diversified form and size according to the species. The Duvernoy´s gland is formed by secretory tubules and excretory ducts. The secretory tubules cells may produce substances of different chemical compositions according to the specie. The histochemical results showed that the majority of the analyzed species present a gland of seromucous type, and only one species has the Duvernoy´s gland classified as mucoserous. The secretion granules present in the cytoplasm of the secretory cells observed in the eletronmicrographics corroborate the histochemical results, since the electron density itself characterizes the cells. The function of the Duvernoy´s gland is directly related to the feeding habit of these serpents and to the way they subjugate preys. The serpents that present the Duvernoy´s gland with mucoserous characteristics subjugate their preys by constriction. On the other hand, the species that have the Duvernoy´s gland of seromucous type use the prey poisoning for feeding. Therefore, the serpents guarantee the success of the immobilization of preys, impeding them to use dangerous defensive tactics against the snake, independently of the use of the constriction.

ASSUNTO(S)

snakes toxinas animal anatomy duvernoy´s gland anatomia animal morfologia animal glândula de duvernoy animal morphology serpentes toxins

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