The pericardium in the deuterostome <Emphasis Type="Italic">Saccoglossus kowalevskii</Emphasis> (Enteropneusta) develops from the ectoderm via schizocoely |
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Authors: | Sabrina Kaul-Strehlow Thomas Stach |
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Institution: | 1.Faculty of Biology, Chemistry, and Pharmacy, Department of Zoology,Systematics and Evolutionary Research, Freie Universit?t Berlin,Berlin,Germany |
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Abstract: | 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 (). |
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