The origin of the coelom in Brachiopoda and its phylogenetic significance

Lüter, Carsten

doi:10.1007/s004359900019

Cited by 59 publications

(45 citation statements)

References 29 publications

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“…Molecular phylogenetic studies indicate that the Phoronida are nested in the phylum Brachiopoda (Halanych et al, 1995, Cohen, 2000. Descriptive studies of gastrulation in rhychonelliform brachiopods (Hemithyris, Terebratulina, Terebratalia) have all derived mesoderm from endoderm (Long and Stricker, 1991;Luter, 2000). These brachiopods gastrulate the same way that phoronids do (Long and Stricker, 1991;Freeman, 1993).…”

Section: Discussionmentioning

confidence: 94%

The Origin of Mesoderm in Phoronids

Freeman

Martindale

2002

Developmental Biology

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Descriptive studies of phoronid development have concluded that the mesoderm of these animals originates from the endoderm during gastrulation. This interpretation has been tested by labeling one blastomere of 4- through 16-cell embryos and examining the position and germ layers occupied by the labeled clones of cells in the larva. No 2 injections gave rise to identical clones of cells, suggesting that the cleavage program does not generate cells of unique identity and that cell fates are established at later developmental time points. In many cases, a relatively large sector composed of ectodermal cells was labeled. When these labeled cells were adjacent to the mouth or anus of the larva, muscle and mesenchyme cells originated from the labeled clones. Under these circumstances, nerve cells also originated from these labeled sectors. These labeling studies also showed that endodermal cells can give rise to mesodermal and neural cells. These results suggest that nerve and muscle cells are induced to form at ectodermal-endodermal boundaries from both germ layers. These marking experiments also confirmed the observation that nerve cells originate both from the apical organ and the trunk region and show for the first time that the intestine originates by ingression of posterior ectoderm.

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Section: Discussionmentioning

confidence: 94%

The Origin of Mesoderm in Phoronids

Freeman

Martindale

2002

Developmental Biology

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“…In the latter species, the mesoderm is thought to originate either from a single anlage growing from near the blastopore toward the anterior pole ("modiWed enterocoely"; Nielsen 1991) or by multipolar ingression over the whole length of the archenteron (Freeman 2000). In the articulates, mesoderm is reported to arise from the archenteron either by lateral outpouching (Long and Stricker 1991), delamination (Freeman 1993) in Terebratalia septentrionalis (Couthouy, 1838) or by outgrowth of an initially compact cell mass in Calloria inconspicua (Sowerby, 1846) and Notosaria nigricans (Sowerby, 1846) (Lüter 2000). There is no evidence for an ectodermal origin of mesodermal elements in Brachiopoda.…”

Section: Cyclostomata and Phylactolaematamentioning

confidence: 96%

“…There is no evidence for an ectodermal origin of mesodermal elements in Brachiopoda. Larval musculature is mainly formed from coelomic myoepithelial cells (Lüter 2000).…”

Section: Cyclostomata and Phylactolaematamentioning

confidence: 99%

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

Gruhl

2009

Zoomorphology

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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 using mainly ultrastructural techniques. Shortly after the onset of gastrulation, an ectodermal cell, which is situated centrally at the prospective anterior pole of the larva, can be recognized by its constricted apical surface and enlarged basal part. It is also distinct from other ectodermal cells by the composition of its cytoplasm. In later stages, it has left the epidermis, lost its epithelial character, and is situated subepithelially, between the basal sides of the ectodermal and endodermal sheets. A blastocoelic cavity is not present at this stage. This cell divides and gives rise to a group of cells forming a muscular and neuronal strand at the anterior side of the larva. The majority of the larval musculature originates from this ingression. Despite this evidence for an ectodermal origin, additional sources of mesoderm can so far not be excluded. The literature on mesoderm origin in Bryozoa is reviewed and the results are compared to known data from other metazoan taxa.

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“…The origin of mesoderm and coelomic compartments has traditionally been given high value for phylogenetic considerations of animal relationships (Hyman 1959;Lüter 2000;Nielsen 2001). The two main modes distinguished, schizocoely and enterocoely, were thought to be associated with two major groups of animals recognized in bilaterians: schizocoely with protostomes and enterocoely with deuterostomes (see e.g.…”

Section: Discussionmentioning

confidence: 99%

“…As a necessary prerequisite for phylogenetic consideration, a clear definition of schizocoely and enterocoely is warranted and has been made explicit by Lüter (2000). According to Lüter (2000), schizocoely is characterized by the ''development of secondary body cavities and coelomic epithelium The posterior portion of the tube-shaped pericardium is more rectangular in sections. It is ventrally accompanied by the developing stomochord (stA).…”

Section: Discussionmentioning

confidence: 99%

The pericardium in the deuterostome Saccoglossus kowalevskii (Enteropneusta) develops from the ectoderm via schizocoely

Kaul-Strehlow

Stach

2011

Zoomorphology

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The origin of mesoderm and coelomic compartments has traditionally been given high value for phylogenetic considerations of animal relationships. Two main modes have been distinguished, associated with the two main groups of animals: schizocoely with protostomes and enterocoely with deuterostomes. During enterocoely, coelomic compartments are formed from the endoderm. Here, we show that the pericardium of the deuterostome Saccoglossus kowalevskii, an enteropneust, is ontogenetically derived from the ectoderm and develops by schizocoely. The pericardium develops from a solid cluster of epidermis cells situated underneath the ectodermal nerve net above the basement membrane of the epidermis. The undifferentiated cells are interconnected by spot desmosomes, become separated from the epidermis and develop a central cavity. Pericardial cells become epithelial, by developing apical adherens junctions, a single apical cilium and basal striated myofibres. The differentiated pericardium possesses a cavity and surrounds a central blood vessel, the heart, situated in the basal extracellular matrix. The pericardium is an integral part of the anterior excretory complex, and comparisons to other deuterostomes indicate that pericardia are homologous despite differing ontogenies. Original data generated for the present study are deposited on MorphDBase (http:\\www.morphdbase.de).

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The origin of the coelom in Brachiopoda and its phylogenetic significance

Cited by 59 publications

References 29 publications

The Origin of Mesoderm in Phoronids

The Origin of Mesoderm in Phoronids

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

The pericardium in the deuterostome Saccoglossus kowalevskii (Enteropneusta) develops from the ectoderm via schizocoely

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