PATHOLOGY

Detailed explanation-1: -Axon of the neuron is surrounded by a sheath called myelin sheath. However, at the areas called nodes of Ranvier, the myelin sheath is not present and hence a gap is created. It helps in the easy conduction of action potential during saltatory conduction. So, the correct answer is ‘Nodes of Ranvier’.

Detailed explanation-2: -The nodes of Ranvier are characterized by short (1um), specialized regions in the axonal membrane that are not insulated by myelin. Although it is bare of myelin at the node, the axon is in direct contact with the microvilli of the Schwann cells in the PNS, or with processes of astrocytes in the CNS (Figure 1).

Detailed explanation-3: -Synapse is the gap between dendrite ends and axon terminals. This is the gap in which neurotransmitters are released for further transmission of nerve impulses to successive neurons.