Editing Axoplasm (section)

==Structure==
Axoplasm is composed of various organelles and cytoskeletal elements. The axoplasm contains a high concentration of elongated [[mitochondria]], [[microfilament]]s, and [[microtubules]].<ref>{{cite book |last=Hammond |first=C. |year=2015 |title =Cellular and Molecular Neurophysiology |pages=433 |publisher=  Academic Press |asin=B00XV3J0UE |edition=4th }}</ref> Axoplasm lacks much of the cellular machinery ([[ribosomes]] and [[Cell nucleus|nucleus]]) required to [[Transcription (genetics)|transcribe]] and translate complex [[proteins]]. As a result, most enzymes and large proteins are transported from the soma through the axoplasm. Axonal transport occurs either by fast or slow transport. Fast transport involves vesicular contents (like organelles) being moved along microtubules by [[motor proteins]] at a rate of 50–400mm per day.<ref>{{cite book |last=Brady |first=S. T. |year=1993 |title=Axonal dynamics and regeneration |publisher=New York: Raven Press |pages=7–36 }}</ref> Slow axoplasmic transport involves the movement of cytosolic soluble proteins and cytoskeletal elements at a much slower rate of 0.02-0.1mm/d. The precise mechanism of slow axonal transport remains unknown but recent studies have proposed that it may function by means of transient association with the fast axonal transport [[vesicle (biology and chemistry)|vesicle]]s.<ref>{{cite journal |last=Young |first=Tang |year=2013 |title=Fast Vesicle Transport Is Required for the Slow Axonal Transport of Synapsin. |journal=Neuroscience |volume=33  |issue=39 |pages=15362–15375 |doi=10.1523/jneurosci.1148-13.2013|pmid=24068803 |pmc=3782618 }}</ref> Though axonal transport is responsible for most organelles and complex proteins present in the axoplasm, recent studies have shown that some translation does occur in axoplasm. This axoplasmic translation is possible due to the presence of localized translationally silent [[mRNA]] and ribonuclear [[protein complexes]].<ref name=Piper>{{cite journal |last1=Piper |first1=M |last2=Holt|first2= C. |year=2004 |title=RNA Translation in Axons. |journal=Annual Review of Cell and Developmental Biology |volume=20  |pages=505–523 |doi=10.1146/annurev.cellbio.20.010403.111746|pmid=15473850 |pmc=3682640}}</ref>