| Term: | notochord nucleus |
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| Note: | This page represents a term created by the combination ("post-composition") of two ontology terms. For more information on the individual terms, click the hyperlinked name. |
| Name: | notochord |
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| Synonyms: | notocord |
| Definition: | Rod-like principal supportive element of the embryo and larva, present in the midline just ventral to the neural tube, and differentiating during the segmentation period to form large vacuolated epithelial cells and a surrounding sheath of fibrous and elastic layers. Layering of the sheath may differ in structure, thickness and development among groups; in cypriniforms there are actually three very thin layers to the sheath. A functional, well developed notochord is present throughout life in certain basal fish groups but not in cypriniforms. |
| Ontology: | Anatomy Ontology [ZFA:0000135] |
| Name: | nucleus |
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| Synonyms: | cell nucleus, horsetail nucleus |
| Definition: | A membrane-bounded organelle of eukaryotic cells in which chromosomes are housed and replicated. In most cells, the nucleus contains all of the cell's chromosomes except the organellar chromosomes, and is the site of RNA synthesis and processing. In some species, or in specialized cell types, RNA metabolism or DNA replication may be absent. |
| Ontology: | GO: Cellular Component [GO:0005634] QuickGO AmiGO |