Wallerian degenratin

wallerian Degenration

1. Wallerian degeneration when a nerve fiber is cut or crushed and thIt  is an active process of  degeneration  that results e part of the axon distal to the injury (i.e. farther from the neuron's cell body) degenerates . process that occurs when a  neuron  is damaged so severely that part of the  axon  is disconnected from the  soma  of the neuron. The disconnected portion of the axon is degenerated .

2. Occurrence:   A related process of dying back or retrograde degeneration known as ' Wallerian -like degeneration' occurs in many neurodegenerative diseases, especially those where  axonal transport  is impaired such as  ALS  and  Alzheimer's disease .  Primary culture  studies suggest that a failure to deliver sufficient quantities of the essential axonal protein  NMNAT2  is a key initiating event . Symptoms: Muscle weakness Limb numbness Altered sensation .

3. Stages of Wallerian degeneration The first stage occurs during the first 12 hr after axotomy at 37°C and is prolonged by low temperatures. Events during the first stage appear to initiate the process leading to Wallerian degeneration or “light the fuse.” The second stage occurs during the period 12–24 hr after axotomy at 37°C. The first stage occurs during the first 12 hr after axotomy at 37°C and is prolonged by low temperatures. Events during the first stage appear to initiate the process leading to Wallerian degeneration. The second stage occurs during the period 12–24 hr after axotomy at 37°C.

4. Zenker's  degeneration Zenker's   degeneration  is a severe glassy or  waxy  hyaline  degeneration  or necrosis of skeletal muscles in acute infectious diseases.   Death of segments of muscle cells that  sometime occurs  in prolonged fevers such as  TYPHOID  or  in   HEPATITIS . Also known as hyaline necrosis. (Friedrich Albert von  Zenker , German pathologist, 1825–89).

5. Symptoms: Dysphagia  ( difficulty swallowing ) Regurgitation  (return of undigested food back into the mouth) Sense of a lump in the neck. Halitosis (smelly breath) due to stagnant food in the pouch. Cough, especially at night. Hoarseness (voice change) Involuntary gurgling noises when swallowing.

6. Diagnosis Zenker's diverticulum is diagnosed using a test called a barium swallow. A barium swallow is a special X-ray that highlights the inside of your mouth, pharynx, and esophagus. A barium swallow fluoroscopy allows your doctor to see how you swallow in motion. Treatment: Treatment options encompass open surgery or transoral rigid or flexible endoscopy and are aimed at eliminating functional out flow obstruction .

7. Pyknosis , or   karyopyknosis ,   ( from Greek  pyknono  meaning "to thicken up, to close or to condense") is also observed in the maturation of  erythrocytes  (a red blood cell) and the  neutrophil  (a type of white blood cell). irreversible  degeneration of a cell in which the nucleus  shrinks  in size and the chromatin condenses to a solid,  structureless  mass or masses. 

8. Occurrence: Pyknosis  occurs in senescent (old) leukocytes and results from preprogrammed cell death (apoptosis). With  pyknosis , the nucleus becomes dense and compact and begins to fragment ( karyorrhexis ) resulting in spheres of dark-staining nuclear chromatin.

9. karyorrhexis Karyorrhexis   (from Greek κάρυον karyon , " kernel, seed or nucleus", and ῥῆξις rhexis , " bursting") is the destructive fragmentation of the nucleus of a dying cell whereby its chromatin is distributed irregularly throughout the cytoplasm. Causes : MPT is caused by many mechanisms, including oxidative stress, and some xenobiotics,increase PT pore opening by a calcium-dependent mechanism.