| Phenotype: | primary motor neuron morphology, abnormal |
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| Note: | This statement combines anatomy and/or ontology terms with phenotype quality terms to create a complete phenotype (EQ) statement. For detailed information on individual terms, click the hyperlinked term name. |
| Name: | primary motor neuron |
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| Synonyms: | primary motoneuron |
| Definition: | Motor neurons that arise during the first day of development. Primary motoneurons have larger diameter cell bodies and axons than secondary motoneurons and are positioned more dorsally and medially than secondary motoneurons. Primary motoneurons are present in a single bilateral pair of clusters in each spinal segment and innervate axial muscle fibers in the corresponding pair of myotomes. Axons make a conspicuous loop around the Mauthner axon before entering the ventral root. |
| Ontology: | Anatomy Ontology [ZFA:0009244] |
| Name: | morphology |
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| Synonyms: | |
| Definition: | A quality of a single physical entity inhering in the bearer by virtue of the bearer's size or shape or structure. |
| Ontology: | Phenotypic Quality Ontology [PATO:0000051] |