Oligodendrocytes and other myelinating cells

Vocabulary flashcards covering key terms related to oligodendrocytes, Schwann cells, myelin structure, myelination, and multiple sclerosis.

Oligodendrocyte

CNS glial cell that myelinates multiple axons (on average ~10 per cell).

Schwann cell

PNS glial cell that can be myelinating or non-myelinating; myelinating Schwann cells wrap a single axon.

Myelin

Lipid-rich, insulating sheath around axons that speeds conduction by enabling saltatory conduction.

Lamella

Concentric layers forming the myelin sheath around an axon.

g-ratio

Ratio of the inner axon diameter to the total fiber diameter (axon plus myelin).

Axon diameter threshold for myelination

Minimum axon thickness required to trigger myelination (about 0.7 mm in PNS or 0.2 mm in CNS in these notes).

Nodes of Ranvier

Naked axonal gaps between myelinated internodes where action potentials are regenerated.

Internode

The myelinated segment of an axon between two nodes of Ranvier.

Paranode

Region at the node where axon–glia interactions organize ion channel clustering for conduction.

Juxtaparanode

Region adjacent to the node where specific ion channels cluster to support conduction.

MBP

Myelin basic protein; major CNS myelin component that helps compact the sheath.

PLP

Proteolipid protein; major CNS myelin protein involved in lamellae integrity.

P0

PNS major myelin protein that mediates lamellae fusion in peripheral myelin.

PMP22

Peripheral myelin protein 22; important component of PNS myelin.

Cx32

Connexin 32; gap junction protein involved in glial interactions with axons.

MAG

Myelin-associated glycoprotein; participates in axon–myelin interactions in CNS and PNS.

GalC

Galactocerebroside; glycosphingolipid used as a myelin marker.

Gangliosides

Glycosphingolipids in myelin; GM4 predominates in CNS, LM1/GM3 in PNS.

OBEC

Olfactory bulb ensheathing cell; glial cell that ensheathes olfactory nerve fibers and guides axon growth.

GFAP

Glial fibrillary acidic protein; glial marker expressed by OBECs and astrocytes.

Nestin

Radial glial marker expressed in OBECs and developing glia.

Vimentin

Intermediate filament/glial marker common in glia, including OBECs.

L1

L1 cell adhesion molecule; marks axons ready for myelination during premyelination.

NCAM

Neural cell adhesion molecule; involved in glia–axon interactions; not found in myelinating Schwann cells.

Premyelination tagging

Expression of adhesion molecules (e.g., L1) that marks axons ready to be myelinated.

OPC

Oligodendrocyte progenitor cell; differentiates into oligodendrocytes upon axon contact.

Demyelination

Loss or damage of the myelin sheath around axons.

Remyelination

Repair or regeneration of myelin after demyelination; often incomplete in disease.

Multiple Sclerosis (MS)

Autoimmune CNS disease characterized by demyelination, inflammation, and variable remyelination.

BBB (Blood–Brain Barrier)

Endothelial barrier that restricts immune cell entry into the CNS; breakdown contributes to MS pathology.