Oligodendrocyte

The oligodendrocyte is a glial cell, one of the support cells of the nervous system, and its job is to make myelin in the central nervous system: the brain and the spinal cord.

Myelin is made of phospholipid membranes stacked in layers, like tape wound around many times. It wraps the axon, the long cable the neuron sends its signal down, holds it in place and insulates it, and with that insulation the impulse travels faster. What stands out is that one oligodendrocyte does not wrap a single cable: one cell extends its arms and wraps several cables at once.

Under the microscope it is recognized by its small nucleus surrounded by rings of cytoplasm, the contents of the cell around the nucleus. And depending on where they sit, they get another name: the interfascicular ones settle between axons that are already myelinated, and the satellite ones sit right up against the cell bodies of neurons.