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Wallerian degeneration is an active process of degeneration that results when a nerve fiber is cut or crushed and the part of the axon distal to the injury (which in most cases is farther from the neuron's cell body) degenerates. [1]
When a nerve axon is severed, the end still attached to the cell body is labeled the proximal segment, while the other end is called the distal segment. After injury, the proximal end swells and experiences some retrograde degeneration, but once the debris is cleared, it begins to sprout axons and the presence of growth cones can be detected.
Transneuronal degeneration is the death of neurons resulting from the disruption of input from or output to other nearby neurons. [1] It is an active excitotoxic process when a neuron is overstimulated by a neurotransmitter (most commonly glutamate) [2] causing the dysfunction of that neuron (either damaging it or killing it) which drives neighboring neurons into metabolic deficit, resulting ...
This nerve movement also applies to the spinal nerves, which can stretch and slacken with movement of the spine. [4] This nerve gliding happens at intraneurial and extraneurial tissue planes. Outside the nerve, a thin layer of tissue similar to adventitia surrounds the nerve upon which the epineurial surface glides. Inside the nerve, fascicles ...
This type of nerve damage may cause paralysis of the motor, sensory, and autonomic functions, and is mainly seen in crush injury. [2] If the force creating the nerve damage is removed in a timely fashion, the axon may regenerate, leading to recovery. Electrically, the nerve shows rapid and complete degeneration, with loss of voluntary motor units.
In 1885, researcher Walther Flemming described dying cells in degenerating mammalian ovarian follicles.The cells showed variable stages of pyknotic chromatin. These stages included chromatin condensation, which Flemming described as "half-moon" shaped and appearing as "chromatin balls," or structures resembling large, smooth, and round electron-dense chromatin masses.
Alan Jackson has been dealing with a health issue for years. In an interview with Jenna Bush Hager on Tuesday's episode of the Today show, the 62-year-old country singer reveals that he has ...
Nervous tissue, also called neural tissue, is the main tissue component of the nervous system.The nervous system regulates and controls body functions and activity. It consists of two parts: the central nervous system (CNS) comprising the brain and spinal cord, and the peripheral nervous system (PNS) comprising the branching peripheral nerves.