Pronunciation: [ˈaksɒn ɹɪˈakʃən] (IPA) 
The spelling of "Axon Reaction" can be explained using the International Phonetic Alphabet (IPA). The first syllable "Ax" is pronounced /æks/ with the vowel sound /æ/ as in "cat" and the consonant sound /ks/ as in "box". The second syllable "on" is pronounced /ɑn/ with the vowel sound /ɑ/ as in "father" and the consonant sound /n/ as in "net". The word refers to the physiological response of a nerve cell's axon to stimuli.
Axon reaction, also known as Wallerian degeneration, refers to a series of cellular and molecular changes that occur in a nerve fiber (axon) following its injury or severance. This process occurs in the peripheral nervous system (PNS) and involves a cascade of events that ultimately lead to the degeneration and removal of the damaged axon segment.
When an axon is injured, either due to trauma, compression, or disease, the affected region undergoes a sequence of structural and functional alterations. The process typically begins with a fragmentation of the axon, where the distal portion distal to the injury site breaks down into small fragments. These fragments are then cleared away by phagocytic cells, mainly by macrophages, through a process known as phagocytosis.
Simultaneously, the myelin sheath that surrounds the axon starts to degrade and disintegrate. Schwann cells, which are responsible for producing myelin in peripheral nerves, participate in this breakdown. Schwann cells also release various molecules that initiate the recruitment of immune cells, such as macrophages, to the injury site to facilitate the clearance of cellular debris.
Over time, the degenerating axon segment is completely removed, and the Schwann cells initiate the process of tissue repair and regeneration. Axon reactions are important in peripheral nerve injury and disease, as they provide the necessary conditions for neuronal regrowth and functional recovery to occur.
