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Introduction: AFX is a bifurcated unibody aortic endograft for the treatment of Abdominal Aortic aneurysms. It consists of an inner metallic endoskeleton with multiple metallic struts covered by a polytetrafluoroethylene graft fabric. The endoskeleton is sutured to the outer fabric only at the proximal and distal ends. The unique design of AFX aims at fixation onto the aortic bifurcation while a proximal cuff ensures sealing at the infrarenal level.Areas covered: Since this endograft design by Endologix has undergone significant changes over the last years, the aim of this article is to present its unique structure and deployment method and discuss the relevant clinical results as well as reported complications and associated concerns.Expert commentary: the AFX stent-graft exhibits very satisfactory clinical mid-term results in abdominal aortic aneurysms treated within the instructions-for-use. Its 'active-seal' concept of infrarenal fixation stemming from the loose conjugation of the fabric material to the endoskeleton can accommodate efficiently to challenging necks with thrombus or morphological irregularities, thereby extending the anatomical sealing zone without exerting significant radial outward force. Long-term results are needed to validate the promising performance of AFX.

Echinoderms have an extensive endoskeleton composed of magnesian calcite and occluded matrix proteins. As biomineralization in sea urchin larvae is sensitive to the Magnesium:Calcium ratio of seawater, we investigated the effects of magnesium deprivation on development and skeletogenesis in the sea urchin Arbacia lixula. We focused on the localization of the skeletogenic cells (primary mesenchyme cells) and the spatial expression of associated genes. Embryos reared in Mg-free seawater exhibited developmental delay from 6-h post-fertilization and at 24 h embryos showed complete lack of biomineral formation. Larvae (48–72 h) exhibited severe skeleton malformations. Fluorescent labelling revealed that the primary mesenchyme cells and the developing skeleton of treated embryos were in an abnormal ectopic location. Expression of the skeleton matrix protein gene (msp130) in the primary mesenchyme cells as seen using in situ hybridization was normal at 24 h. At 48 h this gene was down-regulated in control larvae, but not in treated larvae. Development of the pigment cells, immune cells that, like the skeleton, are mesodermal derivatives, was also impaired. Our results highlight the essential role of Mg in skeleton formation in sea urchin embryos with an indication that this element is also generally important for the development of mesoderm. Abbreviations: hpf: hours post fertilization; PMCs: primary mesenchyme cells; ACC: amorphous calcium carbonate; MgFSW: magnesium-free seawater; FSW: filtered seawater Impact statement Echinoderms have an extensive endoskeleton composed of magnesian calcite We investigated the effects of magnesium deprivation on development and skeletogenesis in the sea urchin Arbacia lixula Magnesium deprivation caused developmental delay and skeleton malformations Primary mesenchyme cells of treated embryos were in an abnormal ectopic location The spatial and temporal expression profile of the skeleton matrix protein gene (msp130) was found to be different from controls Our results highlight the essential role of Mg across developmental processes in sea urchin embryos.

Gladbachus adentatus is a putative chondrichthyan, known only from the holotype specimen, which comprises an articulated endoskeleton complete from head to pelvic region with the squamation also preserved. The scales superficially resemble those of placoderms more than sharks, in having a similar gross morphology, lamellar cellular bone forming the base and upright dentinous tubercles comprising the crown. The odontocytic mesodentine in the tubercles is comparable to that in the Osteostraci and in some acanthodian taxa, known only from isolated scales, and is probably the plesiomorphic form of dentine for Gnathostomata.

The first detailed description of the fossil acanthomorph teleost †Heteronectes chaneti is presented based on a single acid-transfer prepared specimen from the lower Eocene (Ypresian, NP 14) of Bolca, Italy. This genus shows striking cranial asymmetry, with the left orbit displaced toward the top of the skull but failing to reach the dorsal midline. Outside of the orbital region, most paired cranial bones show no clear asymmetry. The postcranial skeleton of †Heteronectes is comparable to that of many ‘generalized’ percomorphs, with a vertebral column comprising 10 abdominal and 14 caudal vertebrae, and a caudal fin with a procurrent spur and 17 principal rays in a I-8/7-I pattern, a caudal-fin endoskeleton consisting of a parphyural, five hypurals, three epurals, and two uroneurals, and pelvic fins with one spine followed by five rays. Evidence for the phylogenetic position of †Heteronectes is reviewed, and a previous interpretation of this genus as a stem member of the percomorph clade Pleuronec...

New, undescribed material of the hybodont shark Tribodus limae, from the Lower Cretaceous of northeastern Brazil, provides new information on the pectoral endoskeleton in this taxon. This allows for a revision of its pectoral morphology, which may be broadly applicable to other Hybodontoidei. Four new specimens of Tribodus with well-preserved pectoral girdles are described, including the first complete, three-dimensionally preserved hybodont scapulocoracoid and partial pectoral fin. These specimens permit examination of the posterior surface of the scapulocoracoid, not visible in previously described hybodonts. Overall pectoral morphology of Tribodus is similar to that of other hybodontiforms and neoselachians. However, the new material shows that the pectoral articulation in Tribodus comprises an oblique posterior ridge on the scapulocoracoid, unlike previous reconstructions of pectoral anatomy in Tribodus and other hybodonts based on two-dimensionally preserved specimens. However, other elasmob...

The histological composition of the galeaspid cephalothoracic skeleton has been much debated: here we attempt to resolve this through the analysis of well-preserved remains of galeaspids from Yunna...

Patches of spherulitic calcified cartilage are described inside the paired fins of the osteostracan Escuminaspis laticeps from the Upper Devonian of Miguasha, Canada, thereby confirming Belles-Isles interpretation of these patches as evidence for paired fin endoskeleton. The distribution of these calcified cartilage patches suggests that the osteostracan paired fin endoskeleton was a single cartilaginous plate located in the lateral half of the fin, and was thus not made up of separate radiais. This morphology resembles that of the endoskeletal disc of the embryonic and larval pectoral fin of piscine gnathostomes, prior to its decomposition into radiais, and may mirror the general condition for the clade that includes osteostracans and gnathostomes.

We describe the morphology of Semionotus, focusing on the Semionotus elegans group from the Newark Supergroup of eastern North America. Our description is based largely on specimens from the Boonton Formation (Early Jurassic) of New Jersey because they are particularly well-preserved and include good material of both the dermal skeleton and the endoskeleton. A single anamestic suborbital distinguishes Semionotus from its sister-genus Lepidotes. We restrict the Semionotidae, defined by the presence of dorsal ridge scales between the nape and dorsal fin as well as a large posteriorly directed process on the epiotic, to two genera, Semionotus and Lepidotes. We restrict the Semionotiformes, defined by four characters and five character losses, to the Lepisosteidae, Macrosemiidae, and Semionotidae. Our study of Semionotus and previous work on Watsonulus suggest new interpretations of characters and character polarities. These data support the hypothesis that the Semionotiformes as we define them are m...

Echinoids are the echinoderm group which has explored and exploited most efficiently the potential of the endoskeleton in a range of extremely advanced and sophisticated adaptive solutions. The most ingenious of these adaptations are employed in the dental apparatus, whose different elements represent a striking example of the versatility of the skeletal tissue. The dental ossicles (jaws, rotulae, compasses and teeth), though having the same basic organization, show a wide range of structural and functional solutions: inorganic phase and organic stroma are variously combined and integrated in a very plastic and adaptable tissue, which is able to fulfil very specific mechanical requirements. On the whole, all the different arrangements shown by the dental elements can be considered as differentiations of the two limit‐models of skeletal microarchitecture, represented respectively by classical porous stereom and a composite lamellar structure. The first structural model is by far the most common: a...

Disarticulated elements in a large, uncompressed regurgitate from Tillywhandland Quarry (Lochkovian), as well as serial sections of an articulated specimen, reveal the three-dimensional shape and structure of fin spines, scapulocoracoid and dermal plates, and the histological structure of dermal and endoskeletal hard tissues of the climatiid acanthodian Climatius reticulatus. Globular calcified cartilage is the only form of mineralization of the head endoskeleton, with the jaws preserved as double-layered globular calcified cartilage. Tooth whorls are borne on both the upper and lower jaws and comprise a vascularized bone base and tooth cusps composed of a vascular network and mesodentine, without a central pulp cavity. The short admedian spine is the only strongly laterally compressed spine; the anterior dorsal fin spine has a wide, splayed base. No evidence was found of large dermal plates between the pectoral fin spine and the median lorical plates, with the prepectoral pinnal plates with spine...

A new genus and two new species of Dercetidae, Rhynchodercetis gracilis, sp. nov. and Dercetoides venator, gen. and sp. nov., from Lower Cenomanian (Upper Cretaceous) beds of Israel are described. The caudal endoskeletons of these new species are the first of the family Dercetidae to be described in detail. Rhynchodercetis gracilis is distinguished mainly by having the relatively longest upper jaw of all species, the presence of an interoperculum, a relatively long caudal vertebra in advance of the caudal endoskeleton, and a convoluted suture between the second and third hypurals. Dercetoides venator represents a Dercetis-like fish with upper and lower jaws that terminate anteriorly at the same level. It is distinguished, mainly, by an unroofed post-temporal fossa, the presence of an interoperculum, two pairs of transverse processes on each precaudal vertebra, and a convoluted suture between the second and third hypurals. An analysis of phylogenetic relationships in the family Dercetidae suggests...

The neurocranium, pectoral fin, and teeth of a second specimen of Squatinactis caudispinatus from the Upper Mississippian Bear Gulch Limestone of Montana are described. The cladodont teeth place this chondrichthyan in the order Cladodontida, but the postorbitally elongate braincase is not similar in detail to those of the marine Mississippian Tamiobatis and the predominantly freshwater xenacanthids. The pectoral fin endoskeleton is most parsimoniously derived from one similar to that of Cladoselache, and reinforces the isolated position of Squatinactis.