Question

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

Short answer

Answer: oligodendrocyte

Step-by-step solution

Understand multiple sclerosis and its pathogenesis

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.

Review the function of each cell type

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.

Select the correct cell type

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.

Key concepts

Oligodendrocyte Apoptosis

Oligodendrocytes are specialized glial cells in the central nervous system that play a crucial role in maintaining the health and function of neuronal pathways. They produce and maintain the myelin sheath, which insulates nerve fibers and facilitates rapid signal conduction. In multiple sclerosis (MS), the apoptosis, or programmed cell death, of oligodendrocytes is a significant pathological event. This process interrupts normal myelin production and maintenance, contributing to the demyelination seen in MS.

When oligodendrocytes undergo apoptosis, the protective myelin sheath around nerve fibers deteriorates. This leads to disrupted nerve signaling, which manifests in the varied neurological symptoms experienced by individuals with MS. The apoptosis of oligodendrocytes is initiated by immune system attacks misdirected towards them, as opposed to their actual role in supporting nerve function.

Furthermore, as oligodendrocytes die, they leave behind damaged axons that can exacerbate the ongoing inflammation and immune response, perpetuating the cycle of damage in MS. Understanding and potentially preventing oligodendrocyte apoptosis remains a critical area of research, with the goal to halt or reverse the progression of MS.

Demyelinating Disease

Demyelinating diseases, like multiple sclerosis, involve the loss or damage of myelin sheaths in the central nervous system. These diseases result in impaired communication between neurons due to the destruction of the insulating material that facilitates the electrical signals along nerve fibers.

In multiple sclerosis, the immune system erroneously targets myelin as a foreign substance, much like it would attack pathogens. This immune-driven attack on the myelin leads to a demyelinating process, where the myelin sheath is diminished or entirely destroyed. Without myelin, nerve fibers are severely compromised in their function.

Symptoms of demyelinating diseases can vary greatly depending on the extent and location of myelin damage. They can include physical manifestations like muscle weakness, coordination problems, numbness, or vision issues, as well as cognitive deficits. Such diversity in symptoms arises because demyelination can essentially "short-circuit" the neurological communication network in unpredictable ways.

Central Nervous System

The central nervous system (CNS) is composed of the brain and spinal cord, serving as the main control center for processing and sending out neurological signals throughout the body. It coordinates not just voluntary actions, but also involuntary processes that are crucial for survival.

In the context of multiple sclerosis, the CNS becomes a battleground where immune cells invade and attack myelin sheaths of nerve fibers. This leads to the formation of lesions or sclerotic plaques, which are characteristic of MS. These plaques cause a disruption in the normal flow of neurological signals, resulting in the symptomatic nature of the disease.

The strategic placement of CNS components in the body makes them highly efficient at executing complex operations. However, due to its complexity, damage to any part of the CNS, such as through demyelination in MS, can lead to significant and diverse neurological deficits. Protecting and preserving CNS integrity is vital in managing diseases like MS, where its functions are directly compromised.