Multiple sclerosis

Multiple sclerosis (MS) is an inflammatory disease of the central nervous system (CNS). This includes the brain, spinal cord and optic nerves.

The CNS is composed of different cell types including neurons and oligodendrocytes. Neurons are composed of a cell body and an extension, the axon, that is surrounded by myelin, a protective sheath. This sheath plays a role in the survival of the axon and allows rapid transmission of information between the brain and the rest of the body. Oligodendrocytes are the cells used to make the myelin sheath.

In MS, myelin is the target of the disease process, which is triggered by an inflammatory reaction. At this signal the macrophages destroy the myelin sheath, respecting the axon at first. The demyelinated lesions are usually well delineated and are called plaques. As the outbreaks progress, the oligodendrocytes will be less and less able to repair damaged myelin sheaths, the axons will become scarce, the old plaque is the place of a scar tissue rich in astrocytes that corresponds to astrocytic gliosis or sclerosis. The study of the cellular and tissue mechanisms of MS seeks to identify factors controlling the inflammatory phase, facilitating remyelination, protecting the axons.


Astrocytic gliosis, silver impregnation X400.

Gliose astrocytaire, imprégnation argentique X400
Macrophages contenant des débris de myéline (bleus) au sein d’une plaque (méthode argentique de Bodian associée à une coloration par le bleu de Luxol , X400)

Macrophages containing myelin (blue) debris in a plaque (silver impregnation method of Bodian associated with a coloration by Luxol fast blue  X400)

Loss of myelin with respect of the axons at the border of a plaque(immunohistochemistry of MBP: Myelin Basic Protein, structural protein of the myelin sheath).

Gliose astrocytaire, imprégnation argentique X400