Myelination

This picture was taken from the following website:
http://neuromuscular.wustl.edu/pics/diagrams/functional/myelinst.jpg

We have been talking about the nervous system this week in class and there were some terms that I encountered in the textbook that I was previously unfamiliar with. The first term is "abaxonal plasma membrane." While this sounds complicated, it is easily described as "one domain that consists of the part of the Schwann ell membrane that is exposed to the external environment, or in our terms, the endoneurium." Two other terms followed in the text, both of which I was unfamiliar with also. The next term goes along with the first and is "adaxonal plasma membrane," which is defined as "the other domain which is in direct contact with the axon." The last term that goes along with these two is "mesaxon." This is "the third domain and is created when the axon is completely enclosed by the Schwann cell membrane." This is also the most complex membrane in that it is "a double membrane that connects the abaxonal and adaxonal membranes and encloses the narrow extracellular space." These terms came up in class because of the myelination process that begins when a Schwann cell surrounds the axon. The easiest way for me to remember these terms is by thinking about the body's anatomy and remembering abduction and adduction. Also, thinking about the endoneurium and epineurium will help me keep the two terms straight.


The information above was taken from the following source: Ross, Michael H., and Wojciech Pawlina. "Nerve Tissue." Histology: A Text and Atlas: With Correlated Cell and Molecular Biology. 6th ed. Philadelphia: Wolters Kluwer/Lippincott Williams & Wilkins Health, 2011. 365. Print.