Morpho-Phisiological Studies of the Dasipodides of the Buenos Aires Province, Argentina (Aspectos morfo-fisiológicos de los dasipódidos bonaerenses)

CASANAVE EMMA BEATRIZ

Foz do Iguacu, Brasil

Conferencia; Reunión de Integración de Morfología Panamericana, y Congreso Panamericano de Anatomía; 2004

Asociaciones Brasileña, Chilena y Argentina de Anatomía.

MORPHO-PHISIOLOGICAL STUDIES OF THE DASIPODIDES OF THE BUENOS AIRES PROVINCE, ARGENTINA Emma Beatriz Casanave Cátedra de Fisiología Animal, Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur, San Juan 670 (8000) Bahía Blanca, Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas, CONICET. E-mail: casanave@criba.edu.ar. Armadillos are neotropical mammals, belonging to the Order Xenarthra, family Dasypodidae, with certain unique features important for biological and biomedical studies. They combine derived and primitive characteristics in both morphology and physiology. I discuss here their general characteristics. I also report a review on some of the original research carried out in my laboratory, with the participation of my group of work, particularly concerning on the species that inhabit Buenos Aires Province, Argentina (Chaetophractus villosus, C. vellerosus, Zaedyus pichiy and Dasypus hybridus). Considering the exclusive pelvian glands, we studied the presence, number and location of the holes corresponding to their opening, establishing that they are present only in C. villosus, C. vellerosus and Euphractus sexcinctus, being their presence or absence a rapid taxonomic character for distinguish between carapaces of C. vellerosus and Z. pichiy. The glands are located inside the concavities of bony protuberances on the internal face of the carapace and consist of apocrine sebaceous and sudoriparous acini in C. villosus and E. sexcinctus and sudoriparous acini in C. vellerosus. The secretion acts as an olfactory stimulus, modifying cerebral electrical activity in both sexes. Concerning the morphology and morphometry of the skull, we investigate the existence of intraspecific and interspecific variation in size and shape, showing sexual dimorphism in the skull and mandibles of C. villosus, C. vellerosus and Z. pichiy. We also obtained discriminant functions, which allowed us to classify by sex the specimens of those Euphractini, and to separate the subspecies of Z. pichiy. The collected material constitutes a unique database of skulls and morphometric information of the species. Reference values for basic haematological parameters of wild and captive populations, morphological and morphometrical characteristics of leucocytes, the ultrastructure of platelets and the mechanism of the haemostasis in the armadillo C. villosus, were also established. Platelet aggregation tests demonstrated the reaction to the agonist, ADP and ristocetine. We established the plasmatic functional fibrinogen concentration and identified the basic mammalian coagulation system, with two activation pathways, contact coagulation system and tisular factor coagulation system, and a common pathway, that leads to the fibrin cloth formation. We also demonstrated the presence of the coagulations factors and that of natural anticoagulation systems (antithrombin III, protein C and protein S), with functional analogy to the human counterpart, establishing their reference ranges. Based in those facts, we demonstrated that the armadillo has a haemostatic system similar to the one of the human being and other mammals. The study of the major plasma lipids classes and their fatty acids (FA) showed that the most abundant lipoproteins were high-density ones (HDL). In the total lipids of plasma, phospholipids (PL) predominated, in correlation with the proportion of HDL. The major PL was phosphatidylcholine, followed by sphingomyelin and lysophosphatidylcholine. Considering the FA profile, n-6 polyunsaturated (PUFA) were the major constituents, followed by saturated and monounsaturated FA, being n.3 PUFA minor components. With our results we hope to enhance basic knowledge of armadillos, providing further insight on their use as animal models in biomedicine, and contributing to the resolution of problems concerning conservation and phylogeny of the group, whose peculiar biological characteristics are key for a better comprehension of the phylogeny of mammals. Supported by SGCYT-UNS, PGI 24/B086; CONICET, PEI 6038/03 and ANPCyT-BID 1201/OC-AR, PICTR 074/02. KEY WORDS: Morphology, armadillo, Mammalia, Xenarthra, Dasypodidae.