Castor canadensis specimens were imported from Canada and released in the wilderness on the Argentinean part of Tierra del Fuego (TDF) in the year 1946. First studies on the development of the beaver population and subsequent environmental changes were conducted four decades later and indicated a strong expansion of these animals, with negative effects on the forest, especially the dominant Nothofagus sp. Between 1999 and 2001, we investigated the density of the beaver population in the Chilean part of TDF and the southern adjacent island Navarino (NAV). Data were mapped into a geographical information system. The mean colony density was 1.03 (range: 0.15-1.91) and 1.1 per km watercourse for 75% of the area of TDF (mainly south and central region) and the total NAV island, respectively. The average number of individuals estimated per colony was five. Based on these findings, the number of beavers in the Chilean part of TDF and on NAV was estimated at 61,300 individuals. The population is increasing and expanding in the Northern region, with a linear rate of 2.6-6.3 km/year.

As many investigators use dogs as experimental models in catheterization-, ligation-, and collateral flow studies, knowledge and awareness of the canine left coronary artery anatomical variation is vital for differentiation between canine and human coronary arterial patterns and canine and human coronary congenital anomalies with or without circulatory importance. The present study was performed to examine and review the various principal subdivisions of the canine left main coronary artery (LMCA) in vascular casts of 20 hearts obtained from cadavers of clinically normal dogs of various ages, breeds and of either sex. A corrosion casting technique using an acrylic resin called Tensol Cement No. 70 and a lower-viscosity acrylic resin called Mercox were used to produce a three-dimensional model of the canine coronary arteries. In our study, all dog hearts were left preponderant and the patterns of the principal subdivisions of the LMCA were grouped into three types: Type 1 occurred in seven of the 20 dogs (35%), Type 2 in 12 of 20 dogs (60%) and Type 3 in one instance (5%). A comparison between the canine divisional patterns of the LMCA in the vascular casts and those reported in the literature showed major agreement.

The syrinx of the duck is characterized by a conspicious sexual dimorphism. In the male mallard, a large osseous bulla is present on the left syringeal side. The present work describes the structures of the male syrinx, which were studied by means of histochemistry, immunohistochemistry and electron microscope. In the right distal tympanum a caudally oriented, protruding structure was observed, which was identified as the valvula syringealis. The syringeal structures like valvula, tympanum, bulla, pessulus and the bronchi were in general covered by a respiratory epithelium, however, local modifications in cellular height and numbers of ciliated and goblet cells were observed. The presence of intrinsic musculature was confirmed by means of immunohistochemistry. Smooth muscle cells reaching from the lateral parts of the inter-bronchial ligament to the medial line and cranially to the inner tympaniform membranes were demonstrated. We suppose that these muscle cells play a role in syringeal sound generation by influencing the tension of the medial tympaniform membranes.

SummaryThis research presents the first anatomical description of the tongue and lingual papillae of the mountain lion (puma). The tongues of three adult male pumas were used in this study. The tongues were dissected and studied firstly by gross and stereomicroscopy. Samples of each part were processed by study with scanning electron microscopy. The margins of the lingual apex were surrounded by numerous filiform papillae, which had a bulky papillary body and a bifurcated tip. On the dorsal surface of the lingual apex, filiform papillae were remarkably pointed and had many secondary projections, which emerged from the base of the main papilla. In the rostral half of the lingual body, filiform papillae were longer, cylindrical and had blunt tips. On the caudal half of the lingual body, filiform papillae gave place to conical ones exhibiting a pointed tip. The fungiform papillae were scattered on the whole dorsal surface of the tongue.On each lateral half of the tongue, four circumvallate papillae were observed and each circumvallate papilla was surrounded by thick and horseshoe-like annular pad, which were composed by pointed conical papillae on the caudal border of the lingual body.The dorsal surface of the circumvallate papilla was covered by many finger-like protrusion, and the tip of each protrusion had a central orifice. Anatomical distribution of lingual papillae was different to other carnivores and represents the adaptation to the feeding habits of this mammal. General morphology of the lingual structures was similar to those of the tiger.

Digital cushions were studied in horses with particular reference to vascularization, tissue constituents and matrix components. The cushions mainly resembled a network of coarse collagen bundles. The areas inbetween the bundles were replenished with loosely woven interstitial connective tissue, myxoid tissue, and fibrocartilage. Expected masses of fat lobules were missing: only solitary adipocytes or small groups of adipocytes were seen. Vascular supply to the cushions was remarkably poor. The mucinous myxoid matrix largely consisted of hyaluronan with little sulphated glycosaminoglycans. Myxoid cells were stellate or ramified in shape and showed a tendency to store glycogen and lipid droplets. Myxoid cells reacted for vimentin and stained for S-100 protein. Moreover, myxoid cells often reacted for neuron specific enolase and glial fibrillary acidic protein. Myxoid tissue continuously transformed into loosely organized interstitial connective tissue with fibroblasts, which remained unreactive when tested for neuroectodermal markers. Myxoid tissue also was not clearly demarcated against irregularly interspersed islets of fibrocartilage or hyaline cartilage. Chondrocytes did not stain for neuron specific enolase but reactivity for S-100 protein and glial fibrillary acidic protein was noted in peripheral regions of fibrocartilage. Single or grouped unilocular fat cells were rarely placed into myxoid areas. Unilocular fat cells stained for vimentin, S-100 protein, and occasionally for glial fibrillary acidic protein but not for neuron specific enolase. Continuous transformation of myxoid tissue into cartilage together with corresponding reactivity for neuroectodermal marker proteins of myxoid cells and peripherally located chondrocytes suggest close relationship between myxoid cells and chondrocytes. The same criteria indicate relationship between myxoid cells and adipocytes. Coarse connective tissue, myxoid tissue, fibrous cartilage, and fat cells are functionally combined to absorb mechanical shock in the horse digital cushions.