Apoptosis of which cell type is a histological hallmark of at least one pathologic subtype of MS plaque? a. neuron b. astrocyte c. oligodendrocyte d. macrophage e. none of the above

Multiple sclerosis (MS) is a chronic inflammatory demyelinating disease of the central nervous system (CNS). It occurs when the immune system attacks the myelin sheath, which is a protective covering around nerve fibers. This process eventually leads to the formation of sclerotic plaques, which can cause a wide range of neurological symptoms.

In order to answer the question, we need to know the function of each cell type listed: a. Neuron: Principal cells of the nervous system that transmit signals. They're responsible for communication within the neural network and aren't involved in myelin production. b. Astrocyte: A type of glial cell that supports neurons by providing nutrients and maintaining the extracellular environment. They also play a role in regulating the blood-brain barrier but aren't involved in myelin production. c. Oligodendrocyte: A type of glial cell responsible for producing and maintaining the myelin sheath that covers nerve fibers in the CNS. d. Macrophage: Immune cells that engulf debris, foreign particles, and dying cells. They play a role in the immune response and inflammation but aren't involved in myelin production.

Since MS is characterized by the damage of the myelin sheath surrounding nerve fibers, the cell type involved in myelin production is most likely to undergo apoptosis in this disease. Therefore, the correct answer is: c. oligodendrocyte This is because oligodendrocytes are responsible for producing and maintaining the myelin sheath, and their apoptosis can be a histological hallmark of at least one pathologic subtype of MS plaque.