Mouse Extraocular Muscles and the Musculotopic Organization of Their Innervation.
Anat Rec (Hoboken)
; 302(10): 1865-1885, 2019 10.
Article
in En
| MEDLINE
| ID: mdl-30993879
ABSTRACT
The organization of extraocular muscles (EOMs) and their motor nuclei was investigated in the mouse due to the increased importance of this model for oculomotor research. Mice showed a standard EOM organization pattern, although their eyes are set at the side of the head. They do have more prominent oblique muscles, whose insertion points differ from those of frontal-eyed species. Retrograde tracers revealed that the motoneuron layout aligns with the general vertebrate plan with respect to nuclei and laterality. The mouse departed in some significant respects from previously studied species. First, more overlap between the distributions of muscle-specific motoneuronal pools was present in the oculomotor nucleus (III). Furthermore, motoneuron dendrites for each pool filled the entire III and extended beyond the edge of the abducens nucleus (VI). This suggests mouse extraocular motoneuron afferents must target specific pools based on features other than dendritic distribution and nuclear borders. Second, abducens internuclear neurons are located outside the VI. We concluded this because no unlabeled abducens internuclear neurons were observed following lateral rectus muscle injections and because retrograde tracer injections into the III labeled cells immediately ventral and ventrolateral to the VI, not within it. This may provide an anatomical substrate for differential input to motoneurons and internuclear neurons that allows rodents to move their eyes more independently. Finally, while soma size measurements suggested motoneuron subpopulations supplying multiply and singly innervated muscle fibers are present, markers for neurofilaments and perineuronal nets indicated overlap in the size distributions of the two populations. Anat Rec, 3021865-1885, 2019. © 2019 American Association for Anatomy.
Key words
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Abducens Nerve
/
Oculomotor Nuclear Complex
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Abducens Nucleus
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Oculomotor Muscles
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Oculomotor Nerve
Limits:
Animals
Language:
En
Journal:
Anat Rec (Hoboken)
Journal subject:
ANATOMIA
Year:
2019
Document type:
Article