The Discoveries of Myelin Structure, Origin, and Function by https://padlet.com/carr777/aiyts08yuhnao6ws Made with a warm hug en-us 2021-02-04 19:55:25 UTC 2025-10-28 16:46:53 UTC hello@padlet.com https://padlet.net/icons/png/1f52c.png 1. Distinction between Myelin and Axons carr777 https://padlet.com/carr777/aiyts08yuhnao6ws/wish/1165842101 Upon general inspection, anatomists were easily able to see that the brain contained distinct areas of grey matter and white matter. While it was also clear that a fatty substance was responsible for the color of white matter, Christian Gottfried Ehrenberg of Berlin University was responsible for distinguishing between the fatty substance (which we now know as myelin) and the axon itself1. 
In 1833, Ehrenberg asserted that “nerve marrow” (myelin) is a separate entity from “brain tubes” (axons)1. The figure below is an illustration from Ehrenberg’s publication, depicting the outer “nerve marrow” and the “brain tube” within. Additionally, Ehrenberg postulated that the grey matter (cell bodies) and white matter (myelinated axons) are continuous1. By making a distinction between the axon and myelin sheath, Ehrenberg’s allowed for in-depth investigations into the complex structures and functions of myelin and axons.

Source: 
(1)https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5010938/#R24
]]> 2021-02-04 19:55:44 UTC https://padlet.com/carr777/aiyts08yuhnao6ws/wish/1165842101 2. Myelinated and Unmyelinated Axons are Differentiated carr777 https://padlet.com/carr777/aiyts08yuhnao6ws/wish/1165842716 Robert Remak furthered neuroscience’s understanding of myelin and where it is located within the nervous system. The illustrations below come from Remak’s 1836 publication where he depicts the structure of the nerves of a 4 week old rabbit1. This illustration shows a myelinated axon and an unmyelinated axon, among other structures1. While working at the University of Berlin, Remark described these two different types of axons and thereby introduced valuable knowledge to the scientific community2. Remark went on to elaborate that unmyelinated axons could be found in the peripheral sympathetic nervous system, as the absence of myelin accounts for the reason they are grey in color3. Remak’s discoveries are significant because they gave important insight into the function of myelin. It became evident that myelin is not completely essential for nerve function, and is undoubtedly an entirely separate entity from the neuron.

Sources: (1)https://www.researchgate.net/figure/The-structure-of-nerve-tissue-by-Robert-Remak-Panel-A-The-structure-of-nerve-fibers-as_fig1_272075992
(2)https://cerebromente.org.br/n17/history/neurons2_i.htm
(3)https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3675270/]]> 2021-02-04 19:55:52 UTC https://padlet.com/carr777/aiyts08yuhnao6ws/wish/1165842716 3. Myelin is Produced from Specialized Cells carr777 https://padlet.com/carr777/aiyts08yuhnao6ws/wish/1165843058 The image below, from Theodor Scwann’s 1839 publication, depicts a calf nerve with a nucleus adjacent to the axon inside of the sheath of Schwann1. While in Belgium, Schwann made the important discovery of the sheath of Schwann1, a membrane that surrounds myelin in the peripheral nervous system2. This sheath only appeared in the peripheral nervous system, and was later determined to be the cytoplasm of myelin-producing Schwann cells2. This discovery made it clear that myelin is produced from specialized cells in the nervous system, and not from axons, as some previously believed. With this knowledge, it became possible to discover the origin and mechanisms behind myelin production, which would later be used to understand myelin-related diseases. 

Sources:
(1)https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5010938/#R24
(2)https://www.biologyonline.com/dictionary/neurilemma]]> 2021-02-04 19:55:56 UTC https://padlet.com/carr777/aiyts08yuhnao6ws/wish/1165843058 4. Myelin Correctly Attributed to Pathology carr777 https://padlet.com/carr777/aiyts08yuhnao6ws/wish/1165843396 Once the structure of myelin began to be deduced, it followed that this knowledge would be applied to clinical observations. The image below is from a 1868 publication of Jean-Martin Charcot’s, illustrating a lesion found in a multiple sclerosis patient1. While working at the Salpêtrière hospital in Paris, Charcot observed that multiple sclerosis lesions could be consistently characterized by “myelin drops and fatty granules”1. Charcot used these observations to invent the histological criteria to diagnose the disease, and his descriptions are very similar to modern multiple sclerosis lesion criteria1. Charcot’s contribution to neuroscience effectively serves as the first correct attribution of myelin pathology to disease, and is especially significant in that his conclusions were widely accurate.  

Sources:
(1)https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5010938/#R24

]]> 2021-02-04 19:56:01 UTC https://padlet.com/carr777/aiyts08yuhnao6ws/wish/1165843396 5. Osmium Staining Technique Reveals Nodes of Ranvier carr777 https://padlet.com/carr777/aiyts08yuhnao6ws/wish/1165843674 Early on, a significant obstacle to understanding the structure of the nervous system was a lack of means to observe its microscopic intricacies. In 1865, Bonn University professor Max Schultze utilized a black osmium staining technique to view myelin more clearly than ever before1. The artifact below is from Louis-Antoine Ranvier’s 1878 publication where he illustrates segmentation of myelin along axons after osmium staining1. Ravier’s application of this staining technique while teaching at Paris Collège de France was monumental because it allowed him to define the nodes of Ranvier, establish that there is one Schwann cell nucleus for each internode, and that each nucleus is an equal distance away from a node1. These discoveries, pioneered by Ranvier, were instrumental to investigations pertaining to the nature of nerve impulses and axonal conduction.

Sources:
(1)https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5010938/#R24]]> 2021-02-04 19:56:05 UTC https://padlet.com/carr777/aiyts08yuhnao6ws/wish/1165843674 Docent: Dr. Kelly Monk carr777 https://padlet.com/carr777/aiyts08yuhnao6ws/wish/1165848371 Dr. Kelly Monk is the director of the Vollum Institute for basic neurological research at Oregon Health and Science University, and she will be an excellent candidate to guide you through this mini-museum1. Dr. Monk completed her postdoctoral training at Stanford University School of Medicine, went on to become an associate professor in the Department of Developmental Biology at Washington University before going to the Vollum Institute1, and is one of the world’s leading researchers on myelin and myelin-producing cells2. Among some of Dr. Monk’s accomplishments are originating a zebrafish model for studying glial biology, discovering receptors responsible for forming PNS and CNS myelin, and identifying genes that may lead to the creation of gene therapy techniques to repair damaged PNS myelin, and even potentially CNS myelin2. Dr. Monk’s work is grounded in the events highlighted in these artifacts, as they were crucial to the development of modern myelin research. 

Sources: 
(1) https://www.ohsu.edu/vollum-institute/kelly-monk-phd
(2) https://www.onwardohsu.org/blog/detail/unraveling-mysteries-myelin]]> 2021-02-04 19:57:10 UTC https://padlet.com/carr777/aiyts08yuhnao6ws/wish/1165848371 Inhibiting Hyaluronidase Activity Via S3 to Promote OPC Maturation Under Demyelinating Conditions carr777 https://padlet.com/carr777/aiyts08yuhnao6ws/wish/1165848632 Research surrounding myelin continues to expand to new territory each year. The image below is from a 2019 study that examined techniques which aimed to promote myelin regeneration and growth1. The researchers found that oligodendrocyte progenitor cell (OPC) maturation can become inhibited by certain hyaluronidases which OPCs express, and discovered that inhibiting these hyaluronidases was effective in enabling myelin growth1. The image presents data indicating that the compound S3, a modified flavonoid which acts to inhibit certain hyaluronidases, is most successful at promoting remyelination1. This research could lead to the creation of novel therapies which would treat patients with conditions that cause demyelination1. This discovery is one of the many modern advances made in the area of myelin research, and it is possible as a result of the foundational knowledge established through investigation into the structure, production, and function of myelin discovered within the presented artifacts.

Source:
(1): https://onlinelibrary.wiley.com/doi/full/10.1002/glia.23715?casa_token=orH7_CFfklYAAAAA%3A4H-29BXtYBzKo1MBDrS3hrkGmZ2MN7AkTQeu9BAxTOAMA3c0_Tn-EbMEOJKUoLIl6COTMykvrepUpw]]> 2021-02-04 19:57:13 UTC https://padlet.com/carr777/aiyts08yuhnao6ws/wish/1165848632