Ultrastructure and formation of the body cavity lining in Phoronis muelleri (Phoronida, Lophophorata)

  title={Ultrastructure and formation of the body cavity lining in Phoronis muelleri (Phoronida, Lophophorata)},
  author={Thomas Bartolomaeus},
Abstract Among other characteristics a trimeric coelomic compartmentation consisting of an anterior protocoel, followed by a mesocoel and a posterior metacoel is traditionally believed to substantiate the sister-group relationship between Lophophorata and Deuterostomia, together forming the Radialia. As molecular data cannot support this hypothesis a reanalysis of the coelomic cavities in Phoronida is undertaken, because corresponding coelomic compartmentation is widely accepted to support the… 

Fine structure of the epistome in Phoronis ovalis: significance for the coelomic organization in Phoronida

A comparison with data on P. muelleri shows that there is no need to assume three different coelomic cavities in Phoronida, in contrast to the predictions of the archicoelomate concept, and a correspondence to the situation in deuterostomes can hardly be found.

Ultrastructure of the body cavities in Phylactolaemata (Bryozoa)

Only species belonging to the bryozoan subtaxon Phylactolaemata possess an epistome, and there is no indication for an excretory function of the forked canal, especially as no excreteory porus was found.

Organization of the coelomic system in Phoronis australis (Lophotrochozoa: Phoronida) and consideration of the coelom in the lophophorates

Which type of coelomic system organization is plesiomorphic for phoronids is determined by transmission electron microscopy and three-dimensional reconstruction and the tripartite coelom appears to be the plesiomorphy for the Brachiozoa.

Organization of the epistome in Phoronopsis harmeri (Phoronida) and consideration of the coelomic organization in Phoronida

It is asserted that the cavity inside the epistome is the preoral coelom corresponding to the true preoralcoelom of the larva of this species, and proving this assertion will require additional study of metamorphosis in this species.

Metamorphic remodeling of morphology and the body cavity in Phoronopsis harmeri (Lophotrochozoa, Phoronida): the evolution of the phoronid body plan and life cycle

The metamorphosis of Phoronopsis harmeri is investigated with light, electron, and laser confocal microscopy and it is proposed that the phoronid ancestor was worm-like animal that possessed preoral, tentacular, and trunk coeloms and gave rise to the body plan of all recentphoronids.

Trimeric coelom organization in the larvae of Phoronopsis harmeri pixell, 1912 (Phoronida, Lophophorata)

Evidence is reported suggesting that the larvae of some Phoronida species actually have a trimeric coelom, and the organization of the body cavity in Phor onida larvae is still discussed.

Ultrastructure of mesoderm formation and development in Membranipora membranacea (Bryozoa: Gymnolaemata)

Mesoderm origin in Bryozoa is largely unknown. In this study, embryonic and early larval stages of Membranipora membranacea, a bryozoan exhibiting a planktotrophic cyphonautes larva, are investigated

Embryogenesis and larval development of Phoronopsis harmeri Pixell, 1912 (Phoronida): dual origin of the coelomic mesoderm

The nature of egg cleavage, gastrulation and the origin of coelomic mesoderm can help to resolve the contradiction between phoronids and brachiopods' status as a monophyletic group within the lophotrochozoan protostomes.

Trochophora larvae: cell-lineages, ciliary bands and body regions. 2. Other groups and general discussion.

  • C. Nielsen
  • Biology
    Journal of experimental zoology. Part B, Molecular and developmental evolution
  • 2005
The embryology of sipunculans, entoprocts, nemertines, platyhelminths, rotifers, ectoproCTs, phoronids, brachiopods, echinoderms and enteropneusts is reviewed with special emphasis on cell-lineage and differentiation of ectodermal structures.

Development, organization, and remodeling of phoronid muscles from embryo to metamorphosis (Lophotrochozoa: Phoronida)

Early steps of phoronid myogenesis reflect the peculiarities of the actinotroch larva: the muscle of the preoral lobe is the first muscle to appear, and it is important for food capture, but always exhibits a complexity that probably results from the long pelagic life, planktotrophy, and catastrophic metamorphosis.



Fine Structure of the Tentacles of Phoronis australis Haswell (Phoronida, Lophophorata)

The epidermis of the tentacles of Phoronis australis consists of six cell types: supporting cells, choanocyte-like sensory cells, both types monociliated, secretory A-cells with a mucous secretion,

The origin of the coelom in Brachiopoda and its phylogenetic significance

Considering endodermal origin as the crucial character for enterocoely, coelom formation through proliferation of a compact, endodermally derived mesodermal cell mass in Brachiopoda is clearly identified as enterocoesly.

Function of lateral cilia in suspension feeding of lophophorates (Brachiopoda, Phoronida, Ectoprocta)

Distribution of the feeding mechanism among phyla, clearance rates, and the lack of fusion of tentacles in brachiopods are discussed and the impingement mechanism previously suggested for lophophorates cannot account for the movements of particles observed here.

The Development of the Brachiopod Crania (Neocrania) anomala (O. F. Müller)and its Phylogenetic Significance

Both groups have originated from a creeping ancestor with a straight gut and the ventral curving of the settling larva and the formation of both valves from dorsal epithelial areas indicate that the brachiopods have a very short ventral side as opposed to the phoronids.

The Median Tentacle of the Larva of Lingula Anatina (Brachiopoda) From Queensland, Australia

The median tentacle of the larvae of Lingula anatina has been investigated in order to obtain information about the morphological implications of its function and its relation to the paired tentacles

Ultrastructure of the basal lamina and its relationship to extracellular matrix of embryos of the starfish Pisaster ochraceus as revealed by anionic dyes

The fact that the basal cell surfaces are often puckered outward at the points of contact suggests that this configuration might be providing a means whereby forces can be transferred from the ECM through the basal lamina to the cells.

Structure and Function of Metazoan Ciliary Bands and Their Phylogenetic Significance

The trochaea theory predicts that Porifera and Cnidaria have only monociliate cells and lack ciliary bands used in filter-feeding, and that the gastroneuralian larvae have downstream-collecting ciliated bands with prototroch and metatroch of compound cilia on multiciliate cells.

Origin of the chordate central nervous system – and the origin of chordates

  • C. Nielsen
  • Biology
    Development Genes and Evolution
  • 1999
Molecular evidence indicates that the protostomian ventral nerve cord plus apical brain is homologous with the vertebrates’ dorsal spinal cord plus brain, which leads to the hypothesis that the two organs evolved from the same area in the latest common bilaterian ancestor, just anterior to the blastopore.

Monophyly of brachiopods and phoronids: reconciliation of molecular evidence with Linnaean classification (the subphylum Phoroniformea nov.)

  • B. Cohen
  • Biology, Geography
    Proceedings of the Royal Society of London. Series B: Biological Sciences
  • 2000
Molecular phylogenetic analyses of aligned 18S rDNA gene sequences from articulate and inarticulate brachiopods representing all major extant lineages, an enhanced set of phoronids and several