Acta Zoologica最新文献

Members of the genus Phrynosoma all exhibit asperities upon the parietal and squamosal. We examined μ-CT scans of the dermatocrania of ontogenetic series of all but two of the species of Phrynosoma, and defined parietal and squamosal “horns”, distinguishing them from tubercles. We counted parietal and squamosal horns and used phylogenetic analysis to reconstruct the plesiomorphic horn numbers for these bones. Based upon this, we propose and test hypotheses of evolutionary homology for these asperities and conclude the following: (1) a plesiomorphic horn array is retained among the species of Phrynosoma; the horns are paramorphs, each identifiable as an evolutionary homologue; (2) an autapomorphic additional pair of parietal horns in P. solare has been recruited from a pair of tubercles associated with the plesiomorphic parietal horns; (3) an additional anterior squamosal horn in P. solare and the Brevicauda species is derived from a tubercle recruited homoplasiously in these taxa; (4) the anteriormost squamosal horn of the plesiomorphic series in the species of the coronatum species group is highly reduced and is subsumed within the posteriormost jugal asperity and (5) an apparent additional squamosal horn exhibited by P. ditmarsi and P. modestum is instead an enlarged submarginal tubercle, a homoplasy for these species.

Rodents can present a large number of morphophysiological variations of the digestive system, allowing them to feed on different diets. In this context, the objective was to describe the morphology of the major salivary glands of Galea spixii. Gross dissection, light microscopy and transmission and scanning electron microscopy assessments of 12 specimens were carried out. The results demonstrate that the G. spixii has four pairs of major salivary glands (parotid, mandibular, zygomatic and sublingual). The glands are lobulated, composed acinar, consisting of mucous and serous acini, with the predominant parotid gland being serous and the zygomatic gland mucous. The mandibular and sublingual glands are mixed. The glands secrete acidic and neutral mucins and commonly present intercalary, striated and excretory ducts. The ultrastructure of the acinar cells suggests the presence of great cellular activity, with a cytoplasm taken by a rough endoplasmic reticulum, many mitochondria, vesicles of electrolucent nature and dispersed chromatin. In conclusion, the major salivary glands of G. spixii are constituted of mucous and serous acini, with serous acini predominant in the mandibular areas. The data also suggest that these rodents may adopt different types of diets, which may explain their adaptability to semi-arid environments.

Ultrastructural observations suggest that lipid material of lizard digital pads derives from degenerating cells in the inter-scale region. Acta Zoologica (Stockholm). Production of epidermal lipids in lizards occurs in mesos- and alpha-layers, including those present in gecko adhesive pads. Lipid material is present over the setae and spatulae of adhesive pads where adhesion takes place. Lipids are hypothesized to influence the process of adhesion keeping hydrophobic the spatula that contacts the substrate. The origin of lipids in pad lamellae that are lost as footsteps during gecko movements is unknown. To maintain setae lipid-coated requires a large and continuous supply of lipids and the most likely source is an epidermal region rich in lipids. Ultrastructural observations show that lipid material is released from sloughed mesos and alpha-cells in the inter-scale region of the lamellae. It is hypothesized that lipids passively move from the hinge region and reach the outer lamella surface. Lipids may also derive from frictional damage of the thin alpha-cells located in the hinge regions during pad extension for climbing or moving on the substrate. The discharged lipid material is likely pushed out from the hinge region by progressive accumulation of secreted material. The present hypothesis presents a simple model illustrating lipid movement from inter-scale regions that coat the setae, contributing to the indicated influence of lipids on spatula adhesion.

The effect of inflammation on tail and limb amputation in lizards is believed to inhibit regeneration. In support of previous studies, the present experimental and immunohistochemical analysis has detected some markers (CD3, CD5, MHCII) of mammalian T-lymphocytes and macrophages of inflammatory type in three different conditions where inflammation is activated. Bioinformatics comparisons indicate that the employed antibodies cross-react with lizard cells. While in regenerating tails few or no immune cells are seen, in microbial-infected and non-regenerating tails, a massive infiltration of mast cells, sparse macrophages and T-lymphocytes is present. In healing limbs, immunolabelled cells likely represented by macrophages and lymphocytes remain in healing tissues of the stump for 2–3 weeks. In the regenerating blastema after heat cauterization of the apical region, a massive infiltration of mast cells and granulocytes occurs at 1–3 days post-injury and a scarring outgrowth is later formed. Although the three markers appear not discriminate the types of immune-cells in lizard, they confirms that immunolabelled cells expressing markers of inflammation are produced in large number in the tail or limbs with strong inflammatory condition. Coupled with previous studies, the present observations support the idea that a high inflammation attracting numerous mast-cells, inflammatory macrophages and T-lymphocyte inhibits regeneration.

Morphological studies are useful to develop analysis with taxonomic, phylogenetic, ecological, physiological and evolutionary approaches. During the life cycle, Anurans carry out gas exchange through different structures such as gills, skin and lungs. In general, the development of lungs during the larval period is scarce known and most studies analyse the morphology and ultrastructure of the lung wall at the adult stage. This study describes the development and morphology of the lung of Trachycephalus typhonius during the prometamorphic and metamorphic periods and adult stage. Lung development starts at premetamorphic stages and continues along the prometamorphic and metamorphic periods with the development of the lung wall vascularization and pulmonary septa. There are remarkable differences comparing the lung framework at the end of metamorphosis to the one in the adult stage, regarding different-order septa and lung wall structure with a well-developed vascular network. Therefore, the final organization occurs during the juvenile period. This work is the first approach to the study of lung development during larval stages in this species and complements previous studies on lung morphology. Also, contributes to the knowledge of lung morphogenesis and could be useful to interpret the respiratory physiology in different environmental conditions.

The oldest known wolf appears 800,000 years ago (Marine Isotope Stage 21) in Eurasia with the unspecialized short-legged old Mammoth steppe wolf Canis lupus bohemica nov. spec. From this species, about 600,000–420,000 years ago (MIS 15-11), the interglacial Canis lupus mosbachensis (Soergel, 1925) short-legged Mosbach grey wolf subspecies roamed Eurasia. In the late Middle Pleistocene, there are two lineages, the southern interglacial grey and northern glacial White wolves in Eurasia. Since 320,000 (MIS 8), the short-legged White wolf Canis lupus spelaeus (Goldfuss, 1823) was the glacial Mammoth steppe-adapted wolf. Parallel to the “cave wolf” (found in the German Zoolithen Cave), the warm climate grey wolf Canis lupus brevis Kuzmina and Sablin, 1994 existed. C. l. spelaeus relates to the Holocene (MIS 1) extant Holarctic Greenland Canis lupus arctos and Siberian Canis lupus albus (Kerr, 1792). The Late Palaeolithic (MIS 2) “Gravettian Goyet dogs” fall into the DNA pool of C. l. spelaeus and are identified herein as pathological bite trauma individuals, which braincase shortened during the healing process. European prehistoric Neolithic dogs seem to have been imported from Central Asia with the Bandkeramik people (approx. 7000 BP) first, which have the stepped frontals originating from grey wolves.

Determination of sex on the base of external morphological features is very difficult in most birds. However, molecular sex identification methods can be used for sexing of these so-called monomorphic bird species. This study analysed the sexual dimorphism of radiographic morphometric features in rock pigeons whose sexes were determined by the molecular sex identification method. Body weights and 21 radiographic measurements of 43 rock pigeons (18 males and 25 females) were taken. Among cranium measurements, the skull width value was statistically significant in terms of gender (p < .01). Length of carpometacarpus (p < .001) was the most statistically significant measurement of the thoracic limb skeleton, and length of tarsometatarsus (p < .01) was the most statistically significant measurement in the pelvic limb. The body weight showed a positive correlation with all measurements. It was observed that 81.4% of the samples were classified correctly with the measurements used in the discriminant analysis. With this study's results, it can be concluded that sex determination in rock pigeons can also be made by radiographic morphometric methods. In addition, more measurements can be obtained with radiographic images compared to external morphometry.

The optical light microscopy and scanning electron microscopy techniques have proven to play a key and noteworthy role in the advancement of morphological studies in general, and in investigating fish scale morphology in particular. These techniques have illustrated several hidden architectural structures in scales that contribute effectively to fish identification and classification. The scale morphological and topological characters such as type, size, shape, lateral surface, focus position, circuli appearance, radii type, lepidonts, and posterior and anterior margin shapes were obtained using macro- and microscopic analysis in six body regions for three size classes of Garra sharq, a cyprinid endemic fish of the Arabian Peninsula. The general scale type in the studied G. sharq species was a basal elasmoid cycloid and a sectioned type. As a protective structure, the scales display several specific characteristics including firm attachment to the fish body, overlapping, and thin structure with a high surface area and high strength. These characteristics improve scale resistance to penetration, increase protection against mechanical injury and microbial infection, enhance scale flexibility, reduce fish weight (reduce friction drag), and increase scale transparency. The scales demonstrate plasticity in focus shape, size, and position in the six fish body parts and fish size groups. The examined scales displayed narrow or wide grooves (radii) in three types including primary, secondary, and tertiary present in all four scale fields (anterior, posterior, and laterals), thus a tetra-sectioned type that is almost specific to the genus Garra. This characteristic also increases scale flexibility. The rostral margin of scales was characterized by the presence of waved and striate types. The lepidont shape and size varied being blunt, flat, pointed, tiny, sharp, short, and long. Some of these scale characters and their morphologies could be used as an alternative tool for identification, classification, and phylogenetic interpretation among the different freshwater fish species and genera.

This study gives a comprehensive description of eyelids movement in little owl and discusses the impact of some surrounding conditions in their kinetic performance. The present study used the video's recording technique to record the kinetic activity of eyelids, besides the anatomical and histological studies of the eyelid's structure. The fundamental eyelid movements can be uniquely and reliably characterized by their anatomical relationship that was confirmed via video recording for their kinetic activity. The levator palpebrae muscle is considered a main generating motor for the upper eyelid; in the little owl, this muscle splits into multiple directions and is distinguished from the levator palpebrae superioris (Lps) and the levator anguli oculi (Lao) muscle. That anatomical pattern of insertion increases the movement of the upper lid. On the other side, the contraction of depressor palpebrae inferioris (Dpi) muscle and the active upward forces of levator palpebrae muscle help in increasing the opening of the eye's fissure. However, the closure process is produced from the passive downward forces and relaxation of the levator palpebrae superioris (Lps), levator anguli oculi (Lao), and depressor palpebrae inferioris muscle, as well as the contraction of retractor anguli oculi lateralis (Raol) and medialis (Raom) muscle. The present results also recorded that nictitating membrane's (Nm) movement is reversely proportionate to the level of kinetic of other eyelids. The mobility of Nm in little owl occurs under the effect of artificial external stress. These anatomical data and sequence video recordings have confirmed that the upper eyelid moves more compared to other eyelids. The authors also suggest that the mobility of eyelids may get stimulated through external pressure force of some surrounding structure like the periorbital sheet. Also, the histological study exhibited that the structure of two eyelids is very similar in the little owl and the variability is showing in the number of cell layers that forms their epithelium of skin and palpebral surfaces, the distribution of pigment granules, and degree of keratinization on their surface. That variability in the histological characters of eyelids may counteract the abrasive forces occurring during the opening and closing processes.

Studying sexual dimorphism facilitates better understanding of the general intersexual divergence of the same species and gives insights into the impact of selective forces on each sex. The sexual dimorphism in anuran external morphology or limb muscles has been well studied in reproductive context, but less so outside the breeding season. Herein, the intersexual differences in 12 external morphological characteristics, 11 forelimb and 12 hindlimb muscles of Hylarana guentheri during non-breeding season were investigated. We found that the males possessed significantly greater head width and tympanum diameter, while the females had significantly larger body size and head length; there was no sexual differences in the examined limb muscles, except for the mass of flexor carpi radialis. The larger body size means greater fertility for the females, and the longer head may be related to the allometry and reduce resource competition. For the males, the wider head is likely correlated with prey size and male–male competition, and also, the larger tympanum and heavier flexor carpi radialis probably aid the productive success. This study provides the comprehensive morphological accounts about the sexual differences of H. guentheri during non-breeding season, which will contribute to clarify the sex-specific resource allocation and reproductive strategies of anurans.