Search results
Results from the WOW.Com Content Network
In the PNS, myelin protein zero (MPZ or P0) has a similar role to that of PLP in the CNS in that it is involved in holding together the multiple concentric layers of glial cell membrane that constitute the myelin sheath. The primary lipid of myelin is a glycolipid called galactocerebroside. The intertwining hydrocarbon chains of sphingomyelin ...
The myelin sheath is not continuous but is segmented along the axon's length at gaps known as the nodes of Ranvier. In the peripheral nervous system the myelination of axons is carried out by Schwann cells. [1] Oligodendrocytes are found exclusively in the CNS, which comprises the brain and spinal cord.
In the first group, a healthy and normal myelin is destroyed by toxic substances, chemicals, or autoimmune reactions. In the second group, the myelin is inherently abnormal and undergoes degeneration. [6] The Poser criteria named this second group dysmyelinating diseases. [7]
Astrocytes can heal partially the lesion leaving a scar. These scars (sclerae) are the known plaques or lesions usually reported in MS. A repair process, called remyelination, takes place in early phases of the disease, but the oligodendrocytes are unable to completely rebuild the cell's myelin sheath.
The myelin sheath that surrounds and protects nerve cells is made by cells called oligodendrocytes. In a person with MS, these cells are lost, so damaged myelin sheaths cannot be repaired.
Lamellar microtubules: They are the microtubules that eventually wrap around the axon, forming the myelin sheath. Actin-based: These include terminal foot processes of podocytes and dendritic spines (small protrusions arising from dendrites). [3] IF-based: The predominant cytoskeletal element within astrocyte processes at birth is microtubules.
The neurilemma is underlain by the myelin sheath (also known as the medullary sheath). In the central nervous system, axons are myelinated by oligodendrocytes, thus lack neurilemma. The myelin sheaths of oligodendrocytes do not have neurilemma because excess cytoplasm is directed centrally toward the oligodendrocyte cell body.
The myelin sheaths separate from the axons at the Schmidt-Lanterman incisures first and then rapidly deteriorate and shorten to form bead-like structures. Schwann cells continue to clear up the myelin debris by degrading their own myelin, phagocytose extracellular myelin and attract macrophages to myelin debris for further phagocytosis. [11]