Search results for "Endoskeleton"
showing 4 items of 4 documents
Spatial and Temporal Expression Patterns in Animals
2006
All metazoan animals comprise a body plan of different complexity. Since it is well established—especially on the basis of molecular and cell biological data—that all metazoan phyla, including the Porifera (sponges) evolved from a common ancestor, the fundamental common principles of pattern formation in Metazoa have been studied to a great extent. Common to all metazoan body plans is the formation of at least one axis that runs from the apical to the basal region; examples for this organization step are the Porifera and the Cnidaria (diploblastic animals). Animals belonging to the triploblasts, the Protostomia (model systems: insects and nematodes) and the Deuterostomia (mammals), comprise…
Ecomorphological inferences in early vertebrates: reconstructing Dunkleosteus terrelli (Arthrodira, Placodermi) caudal fin from palaeoecological data
2017
Our knowledge about the body morphology of many extinct early vertebrates is very limited, especially in regard to their post-thoracic region. The prompt disarticulation of the dermo-skeletal elements due to taphonomic processes and the lack of a well-ossified endoskeleton in a large number of groups hinder the preservation of complete specimens. Previous reconstructions of most early vertebrates known from partial remains have been wholly based on phylogenetically closely related taxa. However, body design of fishes is determined, to a large extent, by their swimming mode and feeding niche, making it possible to recognise different morphological traits that have evolved several times in no…
Effects of magnesium deprivation on development and biomineralization in the sea urchin Arbacia lixula
2019
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 revea…
Cephalic anatomy of Sinentomon erythranum Yin (Protura : Sinentomidae)
1992
Abstract The structure of the head capsule, endoskeletal structures, oral folds, mouthparts, foregut, maxillary and labial glands, and the central nervous system of the Chinese proturan Sinentomon erythranum Yin (Protura : Sinentomidae) have been described. The most significant features are the unusual thickness of the cuticle with numerous serrated lines, the reduction of sutures and the absence of linea ventralis, the simplification of gnathal pieces, and the reduction of the musculature. A comparison with other Protura and Apterygota leads to some morphological and phylogenetical interpretations of the cephalic structures, in particular those concerning the entotrophy.