Final answer:
The myelin sheath is a true white fatty covering that surrounds some neuronal axons, serving as an insulator to enhance the speed of electrical impulse transmission. It is formed by specialized cells in the CNS and PNS, and its damage can lead to neurological diseases like multiple sclerosis.
Step-by-step explanation:
The myelin sheath is indeed a white fatty covering that surrounds the axons of some neurons, making the statement (A) True. It is a lipid-rich layer of insulation formed by glial cells, including oligodendrocytes in the Central Nervous System (CNS) and Schwann cells in the Peripheral Nervous System (PNS). The purpose of the myelin sheath is to facilitate the transmission of electrical signals along the axon, allowing for faster communication within the nervous system. The myelin sheath plays a crucial role in nerve function, and its loss or damage, as witnessed in diseases such as multiple sclerosis (MS), can lead to serious neurological problems. For example, MS is characterized by large-scale loss of the myelin sheath on axons throughout the nervous system, interfering with the electrical signals and causing symptoms like dizziness, fatigue, and loss of motor control.