Teleost Muscles

Cross references:    Teleosts      Motor Neuron Evolution
  Muscle Innervation   
Motor Nerve Organization    
Amphioxus Motor Nerves   Amphioxus Muscles     
Lamprey Muscles      Shark Muscles     Amphibian Muscles      Mammalian Muscles    
  Human Muscles    
Medial Motor Column    
Fast vs. Slow Twitch Muscles  

A review of the organization and evolution of motoneurons innervating the axial musculature of vertebrates. (Goog) - 1987   
See: 
Motor Nerve Organization
    Abstract
http://www.ncbi.nlm.nih.gov/pubmed/3300861    
    PDF
http://deepblue.lib.umich.edu/bitstream/handle/2027.42/26658/0000202.pdf?sequence=1    
from the PDF:
    "The myomeres of bony fish are generally similar to the myomeres of Elasmobranchs. They are complexly folded, with the muscle fibers in the superficial portion of the myomeres running parallel to the long axis of the body, and the deeper fibers running at different, often large (35") angles relative to the body axis."   
    "... the myomeres is composed of two different fiber types as in cartilaginous fish. A band of red fibers typically lies superficially along the side of the body, parallel to the vertebral column ... A much larger mass of white fibers lies deep to the red."   
    "The red fibers have anatomical, biochemical and histochemical features usually associated with aerobic metabolism, including a relatively large number of mitochondria, a high concentration of myoglobin and aerobic enzymes and a dense system of capillaries.
    In contrast the white fibers have lower numbers of mitochondria, lower concentrations of myoglobin and aerobic enzymes and are less well vascularized. Thus, they are specialized for anaerobic metabolism."   
    "The motoneurons in teleosts are located in the ventral portion of the gray matter in the spinal cord.  ... The largest motoneurons in the motor column are located in the extreme dorsal portion of the column, slightly dorsal to the central canal."   
    "In goldfish, as in zebrafish, different populations of motoneurons innervate the functionally different red and white muscle. The red is innervated only by small motoneurons that occupy the ventral part of the motor column. ... The white muscle is innervated by a population of motoneurons that does not innervate red. They are the largest, and they occupy a characteristic position in the extreme dorsal part of the motor column."   

My comment:   
    This is not identical to the comment in Shark Muscles that: 
    "
Accepting that "medial" and "anteriorcorticospinal" are equivalent, this ends my search for the separate origins of the slow and fast twitch motor neurons.  The slow twitch originate in the red nucleus and the fast twitch originate in the vestibulospinal, tectospinal and reticulospinal tracts."    
    Since, in Shark Muscles , both the "Review of the Origin ..." and Wikipedia agree that the red motor neurons are lateral, the location of the red motor neurons in teleosts is similar if "small motoneurons that occupy the ventral part of the motor column", above, means the same as "lateral".  If this is the case, then "extreme dorsal part of the motor column", above, must mean the same as  "medial" and "anteriorcorticospinal".  I need to check on this.      

Searching Google for "Reticulospinal fast twitch" yielded 14,400 hits. 
The Direction Change Concept for Reticulospinal Control of Goldfish ... http://www.jneurosci.org/content/13/10/4101.full.pdf   
The Mauthner cell activates white, fast-twitch muscle fibers   


386<531 From:  Searching PubMed for "retrograde tracing motor neuron" ... 
    See: 
Muscle Innervation
Metabolic profiles of white and red-intermediate spinal motoneurons in the zebrafish.  - 1993 (PubMed)   
    "The motoneurons were identified by retrograde tracing from the trunk muscle and classified, on the basis of their location in the motor column, as those innervating the white, fast glycolytic fibers (WMNs) or those innervating the red and intermediate slow oxidative fibers (RIMNs)."  
My comment:   
    "identified by retrograde tracing ... and classified on the basis of their location in the motor column."  This is very important.  How were they "classified on the basis of their location in the motor column"?  Unfortunately, I don't seem to have access to the full article.  All I have is the abstract.     



SubC-Teleost Muscles
130623 - 0935 (modified) 

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