Cross references:
Teleosts
Motor Neuron Evolution
My comment: 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 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." "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." 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
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